ac -abbr

  1. account
  2. acre
  3. before meals

Ac -abbr

  1. altocumulus
  2. actinium

AC -abbr

  1. air-conditioning
  2. alternating current
  3. before Christ
  4. area code
  5. athletic club

aca·cia [ə-'kā-shə] -n

  1. gum arabic
  2. any of a large genus ( Acacia) of leguminous shrubs and trees of warm regions with leaves pinnate or reduced to phyllodes and white or yellow flower clusters

acad -abbr

  1. academic; academy

ac·a·deme ['a-kə-,dēm, ,a-kə-'] -n

  1. a place of instruction
  2. the academic life, community, or world
    • in the halls of academe
  3. academic
  4. pedant

ac·a·de·mia [,a-kə-'dē-mē-ə] -n

  1. academe

ac·a·dem·ic [,a-kə-'de-mik] -n

  1. a member of an institution of learning
  2. a person who is academic in background, outlook, or methods
  3. academic subjects
    • has no interest in academic s

academic [-mi-kəl] -adj, adv

  1. of, relating to, or associated with an academy or school esp. of higher learning
  2. of or relating to performance in academic courses
    • academic excellence
  3. very learned but inexperienced in practical matters
    • academic thinkers
  4. based on formal study esp. at an institution of higher learning
  5. of or relating to literary or artistic rather than technical or professional studies
  6. theoretical, speculative
    • an academic question
  7. having no practical or useful significance
  8. conforming to the traditions or rules of a school (as of literature or art) or an official academy : conventional
    • academic painting

academic freedom -n

  1. freedom to teach or to learn without interference (as by government officials)

ac·a·de·mi·cian [,a-kə-də-'mi-shən, ə-,ka-də-] -n

  1. a member of an academy for promoting science, art, or literature
  2. a follower of an artistic or philosophical tradition or a promoter of its ideas
  3. academic

ac·a·dem·i·cism [,a-kə-'de-mə-,si-zəm] -n

  1. the doctrines of Plato's Academy
  2. the skeptical doctrines of the later Academy holding that nothing can be known
  3. a formal academic quality (as in art or music)
  4. purely speculative thoughts and attitudes

academic year -n

  1. the annual period of sessions of an educational institution usu. beginning in September and ending in June

acad·e·my [ə-'ka-də-mē] -n

  1. a school usu. above the elementary level
  2. a private high school
  3. a high school or college in which special subjects or skills are taught
  4. higher education used with the
    • the functions of the academy in modern society
  5. the school for advanced education founded by Plato
  6. the philosophical doctrines associated with Plato's Academy
  7. a society of learned persons organized to advance art, science, or literature
  8. a body of established opinion widely accepted as authoritative in a particular field

Aca·di·an [ə-'kā-dē-ən, a-] -n, adj

  1. a native or inhabitant of Acadia
  2. a descendant of the French-speaking inhabitants of Acadia expelled after the French loss of the colony in 1755
  3. cajun

acai [,ä-,sä-'ē, -sī-'ē] -n

  1. a small dark purple fleshy berrylike fruit of a tall slender palm ( Euterpe oleracea) of tropical Central and South America that is often used in beverages
  2. the palm

acan·tho·ceph·a·lan [ə-,kan(t)-thə-'se-fə-lən] -n, adj

  1. spiny-headed worm

acan·thus [ə-'kan(t)-thəs] -n

  1. any of a genus ( Acanthusof the family Acanthaceae, the acanthus family) of prickly perennial herbs chiefly of the Mediterranean region
  2. an ornamentation (as in a Corinthian capital) representing or suggesting the leaves of the acanthus

ac·a·ri·a·sis [,a-kə-'rī-ə-səs] -n

  1. infestation with or disease caused by mites

acar·i·cide [ə-'ker-ə-,sīd, -'ka-rə-] -n, adj

  1. a pesticide that kills mites and ticks

ac·a·rid ['a-kə-rəd] -n, adj

  1. any of an order (Acari syn. Acarina) of arachnids including the mites and ticks

ac·a·rus ['a-kə-rəs] -n

  1. mite
  2. one of a formerly extensive genus ( Acarus)

acat·a·lec·tic [(,)ā-,ka-tə-'lek-tik] -adj, n

  1. not catalectic
    • acatalectic verse

acau·les·cent [,ā-kȯ-'le-sᵊnt] -adj

  1. having no stem or appearing to have none

acc -abbr

  1. accusative

ac·cede [ak-'sēd, ik-] -vi

  1. to become a party (as to an agreement)
  2. to express approval or give consent : give in to a request or demand
  3. approach
  4. to enter upon an office or position

accel -abbr

  1. accelerando

ac·ce·le·ran·do [(,)ä-,che-lə-'rän-(,)dō; ik-,se-, (,)ak-] -adv or adj

  1. gradually faster used as a direction in music

accelerando -n

  1. a gradual increase in tempo

ac·cel·er·ant [ik-'se-lə-rənt, ak-] -n

  1. a substance used to accelerate a process (as the spreading of a fire)

ac·cel·er·ate [-lə-,rāt] -vb, adv

  1. to bring about at an earlier time
    • accelerate their departure
  2. to cause to move faster
    • accelerated his steps
  3. to cause to undergo acceleration
  4. to hasten the progress or development of
    • accelerate our efforts
  5. increase
    • accelerate food production
  6. to enable (a student) to complete a course in less than usual time
  7. to speed up (as a course of study)
  8. to move faster : gain speed
    • the car slowly accelerated
  9. grow, increase
    • inflation was accelerating
  10. to follow an accelerated educational program

ac·cel·er·a·tion [ik-,se-lə-'rā-shən, (,)ak-] -n

  1. the act or process of accelerating : the state of being accelerated
  2. the rate of change of velocity with respect to time
  3. change of velocity

acceleration of gravity

  1. the acceleration of a body in free fall under the influence of earth's gravity expressed as the rate of increase of velocity per unit of time and assigned the standard value of 980.665 centimeters per second per second called also g

acceleration principle -n

  1. a theory in economics: an increase or decrease in income induces a corresponding but magnified change in investment

ac·cel·er·a·tive [ik-'se-lə-,rā-tiv, ak-] -adj

  1. of, relating to, or tending to cause acceleration : accelerating

ac·cel·er·a·tor [ik-'se-lə-,rā-tər, ak-] -n

  1. : one that accelerates: as
  2. a muscle or nerve that speeds the performance of an action
  3. a device (as a pedal) for controlling the speed of a motor vehicle engine
  4. a substance that speeds a chemical reaction
  5. an apparatus for imparting high velocities to charged particles (as electrons)
  6. an item of computer hardware that increases the speed at which a program or function operates
    • a graphics accelerator

ac·cel·er·om·e·ter [ik-,se-lə-'rä-mə-tər, ak-] -n

  1. an instrument for measuring acceleration or for detecting and measuring vibrations

ac·cent ['ak-,sent, ak-'] -vt

  1. to pronounce with accent : stress
  2. to mark with a written or printed accent
  3. to give prominence to : make more prominent
  4. an articulative effort giving prominence to one syllable over adjacent syllables
  5. the prominence thus given a syllable
  6. : a distinctive manner of expression: as
  7. an individual's distinctive or characteristic inflection, tone, or choice of words usu. used in pl.
  8. a way of speaking typical of a particular group of people and esp. of the natives or residents of a region
  9. rhythmically significant stress on the syllables of a verse usu. at regular intervals
  10. utterance
  11. a mark (as , , ) used in writing or printing to indicate a specific sound value, stress, or pitch, to distinguish words otherwise identically spelled, or to indicate that an ordinarily mute vowel should be pronounced
  12. an accented letter
  13. greater stress given to one musical tone than to its neighbors
  14. accent mark
  15. emphasis laid on a part of an artistic design or composition
  16. an emphasized detail or area
  17. a small detail in sharp contrast with its surroundings
  18. a substance or object used for emphasis
  19. : a mark placed to the right of a letter or number and usu. slightly above it: as
  20. a double prime
  21. prime
  22. special concern or attention : emphasis
    • an accent on youth

accent mark -n

  1. accent
  2. accent
  3. a symbol used to indicate musical stress
  4. a mark placed after a letter designating a note of music to indicate in which octave the note occurs

ac·cen·tu·al [ak-'sen(t)-sh(ə-)wəl, ik-] -adj, adv

  1. of, relating to, or characterized by accent
  2. based on accent rather than on quantity or syllabic recurrence
    • accentual poetry

ac·cen·tu·ate [ik-'sen(t)-shə-,wāt, ak-] -vt, n

  1. accent, emphasize
  2. intensify
    • accentuate s the feeling of despair

ac·cept [ik-'sept, ak- also ek-] -vb, adv, n

  1. to receive willingly
    • accept a gift
  2. to be able or designed to take or hold (something applied or added)
    • a surface that will not accept ink
  3. to give admittance or approval to
    • accept her as one of the group
  4. to endure without protest or reaction
    • accept poor living conditions
  5. to regard as proper, normal, or inevitable
    • the idea is widely accept ed
  6. to recognize as true : believe
    • refused to accept the explanation
  7. to make a favorable response to
    • accept an offer
  8. to agree to undertake (a responsibility)
    • accept a job
  9. to assume an obligation to pay
  10. to take in payment
    • we don't accept personal checks
  11. to receive (a legislative report) officially
  12. to receive favorably something offered usu. used with of
    • a heart more disposed to accept of his -- Jane Austen

ac·cept·able [ik-'sep-tə-bəl, ak- also ek-] -adj, n, adv

  1. capable or worthy of being accepted
    • no compromise would be acceptable
  2. welcome, pleasing
    • compliments are always acceptable
  3. barely satisfactory or adequate
    • performances varied from excellent to acceptable

ac·cep·tance [ik-'sep-tən(t)s, ak-] -n

  1. an agreeing either expressly or by conduct to the act or offer of another so that a contract is concluded and the parties become legally bound
  2. the quality or state of being accepted or acceptable
  3. the act of accepting : the fact of being accepted : approval
  4. the act of accepting a time draft or bill of exchange for payment when due according to the specified terms
  5. an accepted draft or bill of exchange
  6. acceptation

ac·cep·tant [-tənt] -adj

  1. willing to accept : receptive

ac·cep·ta·tion [,ak-,sep-'tā-shən] -n

  1. acceptance
  2. favorable reception or approval
  3. a generally accepted meaning of a word or understanding of a concept

ac·cept·ed -adj, adv

  1. generally approved or used
    • an accepted convention

ac·cept·er [ik-'sep-tər, ak-] -n

  1. one that accepts
  2. acceptor

ac·cep·tive [ak-'sep-tiv] -adj

  1. acceptable
  2. receptive

ac·cep·tor [ik-'sep-tər, ak-] -n

  1. accepter
  2. one that accepts an order or a bill of exchange
  3. an atom, molecule, or subatomic particle capable of receiving another entity (as an electron) esp. to form a compound

ac·cess ['ak-,ses also ik-'ses] -n

  1. onset
  2. a fit of intense feeling : outburst
  3. permission, liberty, or ability to enter, approach, or pass to and from a place or to approach or communicate with a person or thing
  4. freedom or ability to obtain or make use of something
  5. a way or means of access
  6. the act or an instance of accessing
  7. an increase by addition
    • a sudden access of wealth

access -vt

  1. to get at : gain access to
    • access ed the computer by phone

ac·ces·si·ble [ik-'se-sə-bəl, ak-, ek-] -adj, n, adv

  1. providing access
  2. capable of being reached
    • accessible by rail
  3. being within reach
    • fashions at accessible prices
  4. easy to communicate or deal with
    • accessible people
  5. capable of being influenced : open
    • accessible to new ideas
  6. capable of being used or seen : available
    • the collection is not currently accessible
  7. capable of being understood or appreciated
    • the author's most accessible stories
    • an accessible film

ac·ces·sion [ik-'se-shən, ak-] -n, adj

  1. increase by something added
  2. acquisition of additional property (as by growth or increase of existing property)
  3. something added : acquisition
  4. the act of assenting or agreeing
  5. the act of becoming joined : adherence
  6. the act by which one nation becomes party to an agreement already in force between other powers
  7. an act of coming near or to : approach, admittance
  8. the act of coming to high office or a position of honor or power
    • her accession to power
  9. a sudden fit or outburst : access

accession -vt

  1. to record in order of acquisition

ac·ces·so·ri·al [,ak-sə-'sȯr-ē-əl] -adj

  1. of or relating to an accessory
    • accessorial liability
  2. of, relating to, or constituting an accession : supplementary
    • accessorial services

ac·ces·so·rise [ik-'se-sə-,rīz, ak-] -vb

(variant of accessorize)

  1. to furnish with accessories
  2. to wear clothing accessories

ac·ces·so·rize [ik-'se-sə-,rīz, ak-] -vb

  1. to furnish with accessories
  2. to wear clothing accessories

ac·ces·so·ry [ik-'se-sə-rē, ak-, ek-, -'ses-rē, also ə-'se-] -n

  1. a person not actually or constructively present but contributing as an assistant or instigator to the commission of an offense called also accessory before the fact
  2. a person who knowing that a crime has been committed aids or shelters the offender with intent to defeat justice called also accessory after the fact
  3. a thing of secondary or subordinate importance : adjunct
  4. an object or device not essential in itself but adding to the beauty, convenience, or effectiveness of something else
    • auto accessories
    • clothing accessories

accessory -adj

  1. assisting as a subordinate
  2. contributing to a crime but not as the chief agent
  3. aiding or contributing in a secondary way : supplementary
  4. present in a minor amount and not essential as a constituent
    • an accessory mineral in a rock

accessory fruit -n

  1. a fruit (as the apple) of which a conspicuous part consists of tissue other than that of the ripened ovary

accessory nerve -n

  1. either of a pair of motor nerves that are the 11th cranial nerves of higher vertebrates, arise from the medulla and the upper part of the spinal cord, and supply chiefly the pharynx and muscles of the upper chest, back, and shoulders

access time -n

  1. the time lag between the time stored information (as in a computer) is requested and the time it is delivered

ac·ciac·ca·tu·ra [(,)ä-,chä-kə-'tu̇r-ə] -n

  1. a discordant note sounded with a principal note or chord and immediately released

ac·ci·dence ['ak-sə-dən(t)s, -,den(t)s] -n

  1. a part of grammar that deals with inflections

ac·ci·dent ['ak-sə-dənt, -,dent; 'aks-dənt] -n

  1. an unforeseen and unplanned event or circumstance
  2. lack of intention or necessity : chance
    • met by accident rather than by design
  3. an unfortunate event resulting esp. from carelessness or ignorance
  4. an unexpected and medically important bodily event esp. when injurious
    • a cerebrovascular accident
  5. an unexpected happening causing loss or injury which is not due to any fault or misconduct on the part of the person injured but for which legal relief may be sought
  6. used euphemistically to refer to an involuntary act or instance of urination or defecation
  7. a nonessential property or quality of an entity or circumstance
    • the accident of nationality

ac·ci·den·tal [,ak-sə-'den-tᵊl] -adj, adv, n

  1. arising from extrinsic causes : incidental, nonessential
  2. occurring unexpectedly or by chance
  3. happening without intent or through carelessness and often with unfortunate results

accidental -n

  1. a nonessential property
  2. a note foreign to a key indicated by a signature
  3. a prefixed sign indicating an accidental

accident insurance -n

  1. insurance against loss through accidental bodily injury to the insured

accidentprone -adj

  1. having a greater than average number of accidents
  2. having personality traits that predispose to accidents

ac·cid·ie ['ak-sə-dē] -n

  1. acedia

ac·cip·i·ter [ak-'si-pə-tər, ik-] -n, adj or n

  1. any of a genus ( Accipiter) of medium-sized forest-inhabiting hawks that have short broad wings and a long tail and a characteristic flight pattern of several quick flaps and a glide

ac·claim [ə-'klām] -vb, n

  1. applaud, praise
  2. to declare by acclamation
  3. to shout praise or applause

acclaim -n

  1. the act of acclaiming
  2. praise, applause

ac·cla·ma·tion [,a-klə-'mā-shən] -n

  1. a loud eager expression of approval, praise, or assent
  2. an overwhelming affirmative vote by cheers, shouts, or applause rather than by ballot

ac·cli·mate ['a-klə-,māt; ə-'klī-mət, -,māt] -vb

  1. to adapt to a new temperature, altitude, climate, environment, or situation
  2. to become acclimated

ac·cli·ma·tion [,a-klə-'mā-shən, -,klī-] -n

  1. the process or result of acclimating
  2. physiological adjustment by an organism to environmental change

ac·cli·ma·tise [ə-'klī-mə-,tīz] -vb, n

(variant of acclimatize)

  1. acclimate

ac·cli·ma·tize [ə-'klī-mə-,tīz] -vb, n

  1. acclimate

ac·cliv·i·ty [ə-'kli-və-tē, a-] -n

  1. an ascending slope (as of a hill)

ac·co·lade ['a-kə-,lād, -,läd] -n

  1. a ceremonial embrace
  2. a ceremony or salute conferring knighthood
  3. a mark of acknowledgment : award
  4. an expression of praise
  5. a brace or a line used in music to join two or more staffs carrying simultaneous parts

ac·com·mo·date [ə-'kä-mə-,dāt] -vb, adj, n

  1. to make fit, suitable, or congruous
  2. to bring into agreement or concord : reconcile
  3. to provide with something desired, needed, or suited (as a helpful service, a loan, or lodgings)
  4. to make room for
  5. to hold without crowding or inconvenience
  6. to give consideration to : allow for
    • accommodate the special interests of various groups
  7. to adapt oneself
  8. to undergo visual accommodation

ac·com·mo·dat·ing [-,dā-tiŋ-lē] -adj, adv

  1. willing to please : helpful, obliging

ac·com·mo·da·tion [ə-,kä-mə-'dā-shən] -n, adj

  1. : something supplied for convenience or to satisfy a need: as
  2. lodging, food, and services or traveling space and related services usu. used in pl.
    • tourist accommodation s on the boat
    • overnight accommodation s
  3. a public conveyance (as a train) that stops at all or nearly all points
  4. loan
  5. : the act of accommodating : the state of being accommodated: as
  6. the providing of what is needed or desired for convenience
  7. adaptation, adjustment
  8. a reconciliation of differences : settlement
  9. the automatic adjustment of the eye for seeing at different distances effected chiefly by changes in the convexity of the crystalline lens
  10. the range over which such adjustment is possible

ac·com·mo·da·tion·ist [-'dā-sh(ə-)nist] -n

  1. one who adapts to or compromises with an opposing view
  2. a black who adapts to the ideals or attitudes of whites

accommodationist -adj

  1. favoring or practicing accommodation or compromise

accommodation ladder -n

  1. a light ladder or stairway hung over the side of a ship for ascending from or descending to small boats

ac·com·pa·ni·ment [ə-'kəm-pə-nē-mənt, -'kəmp-nē-] -n, adj

  1. an instrumental or vocal part designed to support or complement a melody
  2. an addition (as an ornament) intended to give completeness or symmetry : complement
  3. an accompanying situation or occurrence : concomitant

ac·com·pa·nist [ə-'kəmp-nist, -'kəm-pə-] -n

  1. one (as a pianist) who plays an accompaniment

ac·com·pa·ny [ə-'kəmp-nē, -'kämp-; -'kəm-pə-, -'käm-] -vb

  1. to go with as an associate or companion
  2. to perform an accompaniment to or for
  3. to cause to be in association
    • accompanied their advice with a warning
  4. to be in association with
    • the pictures that accompany the text
  5. to perform an accompaniment

ac·com·plice [ə-'käm-pləs, -'kəm-] -n

  1. one associated with another esp. in wrongdoing

ac·com·plish [ə-'käm-plish, -'kəm-] -vt, adj, n

  1. to bring about (a result) by effort
    • have much to accomplish today
  2. to bring to completion : fulfill
    • we can accomplish the job in an hour
  3. to succeed in reaching (a stage in a progression)
    • would starve before accomplish ing half the distance -- W. H. Hudson 1922
  4. to equip thoroughly
  5. perfect

ac·com·plished -adj

  1. proficient as the result of practice or training
    • an accomplished dancer
  2. skillfully done or produced
    • an accomplished film
  3. having many social accomplishments
  4. established beyond doubt or dispute
    • an accomplished fact

ac·com·plish·ment [ə-'käm-plish-mənt, -'kəm-] -n

  1. the act of accomplishing : completion
  2. something that has been accomplished : achievement
  3. a quality or ability equipping one for society
  4. a special skill or ability acquired by training or practice

ac·cord [ə-'kȯrd] -vb

  1. to bring into agreement : reconcile
  2. to grant or give esp. as appropriate, due, or earned
  3. to arrive at an agreement
  4. to give consent
  5. to be consistent or in harmony : agree usu. used with with
    • a theory that accord s with the known facts

accord -n

  1. agreement, conformity
    • acted in accord with the company's policy
  2. a formal reaching of agreement : compact, treaty
  3. balanced interrelationship : harmony
  4. assent
  5. voluntary or spontaneous impulse to act
    • gave generously of their own accord

ac·cor·dance [ə-'kȯr-dᵊn(t)s] -n

  1. agreement, conformity
    • in accordance with a rule
  2. the act of granting

ac·cor·dant [-dᵊnt] -adj, adv

  1. consonant, agreeing
  2. harmonious, correspondent

according as -conj

  1. in accord with the way in which
  2. depending on how
  3. depending on whether : if

ac·cord·ing·ly [ə-'kȯr-diŋ-lē] -adv

  1. in accordance : correspondingly
  2. consequently, so

according to -prep

  1. in conformity with
  2. as stated or attested by
  3. depending on

ac·cor·di·on [ə-'kȯr-dē-ən] -n

  1. a portable keyboard wind instrument in which the wind is forced past free reeds by means of a hand-operated bellows

accordion -adj

  1. folding or creased or hinged to fold like an accordion
    • an accordion pleat
    • an accordion door

ac·cost [ə-'kȯst, -'käst] -vt

  1. to approach and speak to often in a challenging or aggressive way

ac·couche·ment [,a-,küsh-'mäⁿ, ə-'küsh-,] -n

  1. the time or act of giving birth

ac·cou·cheur [,a-,kü-'shər] -n

  1. one that assists at a birth
  2. obstetrician

ac·count [ə-'kau̇nt] -n

  1. reckoning, computation
  2. a record of debit and credit entries to cover transactions involving a particular item or a particular person or concern
  3. a statement of transactions during a fiscal period and the resulting balance
  4. a statement explaining one's conduct
  5. a statement or exposition of reasons, causes, or motives
    • no satisfactory account of these phenomena
  6. a reason for an action : basis
    • on that account I must refuse
  7. a formal business arrangement providing for regular dealings or services (as banking, advertising, or store credit) and involving the establishment and maintenance of an account
  8. client, customer
  9. money deposited in a bank account and subject to withdrawal by the depositor
  10. value, importance
    • it's of no account to me
  11. esteem
    • stood high in their account
  12. advantage
    • turned her wit to good account
  13. careful thought : consideration
    • have to take many things into account
  14. a usu. mental record : track
    • keep account of all you do
  15. a description of facts, conditions, or events : report, narrative
    • the newspaper account of the fire
    • by all account s they're well-off
  16. performance
    • a straightforward account of the sonata

account -vb

  1. to think of as : consider
    • account s himself lucky
  2. to probe into : analyze
  3. to furnish a justifying analysis or explanation used with for
    • couldn't account for the loss
  4. to be the sole or primary factor used with for
    • the pitcher account ed for all three putouts
  5. to bring about the capture, death, or destruction of something used with for
    • account ed for two rabbits

ac·count·abil·i·ty [ə-,kau̇n-tə-'bi-lə-tē] -n

  1. the quality or state of being accountable
  2. an obligation or willingness to accept responsibility or to account for one's actions
    • public officials lacking accountability

ac·count·able [ə-'kau̇n-tə-bəl] -adj, n, adv

  1. subject to giving an account : answerable
    • held her accountable for the damage
  2. capable of being accounted for : explainable

ac·coun·tan·cy [ə-'kau̇n-tᵊn(t)-sē] -n

  1. the profession or practice of accounting

ac·coun·tant [ə-'kau̇n-tᵊnt] -n

  1. one that gives an account or is accountable
  2. one who is skilled in the practice of accounting or who is in charge of public or private accounts

accountant -adj

  1. accountable, answerable
    • I stand accountant for as great a sin -- Shak.

account executive -n

  1. a business executive (as in an advertising agency) responsible for dealing with a client's account

ac·count·ing [ə-'kau̇n-tiŋ] -n

  1. the system of recording and summarizing business and financial transactions and analyzing, verifying, and reporting the results
  2. the principles and procedures of accounting
  3. work done in accounting or by accountants
  4. an instance of applied accounting or of the settling or presenting of accounts
  5. account

account payable -n

  1. the balance due to a creditor on a current account

account receivable -n

  1. a balance due from a debtor on a current account

ac·cou·tre [ə-'kü-tər] -vt

  1. to provide with equipment or furnishings : outfit

ac·cou·tre·ment [ə-'kü-trə-mənt, -'kü-tər-mənt] -n

  1. equipment, trappings
  2. a soldier's outfit usu. not including clothes and weapons usu. used in pl.
  3. an accessory item of clothing or equipment usu. used in pl.
  4. the act of accoutring
  5. an identifying and often superficial characteristic or device usu. used in pl.
    • accoutrement s of power that define our diplomacy -- Elizabeth Drew

ac·cred·it [ə-'kre-dət] -vt, adj, n

  1. : to give official authorization to or approval of:
  2. to provide with credentials
  3. to send (an envoy) with letters of authorization
  4. to recognize or vouch for as conforming with a standard
  5. to recognize (an educational institution) as maintaining standards that qualify the graduates for admission to higher or more specialized institutions or for professional practice
  6. to consider or recognize as outstanding
  7. attribute, credit

ac·crete [ə-'krēt] -vb

  1. to grow or become attached by accretion
  2. to cause to adhere or become attached
  3. accumulate

ac·cre·tion [ə-'krē-shən] -n, adj

  1. : the process of growth or enlargement by a gradual buildup: as
  2. increase by external addition or accumulation (as by adhesion of external parts or particles)
  3. the increase of land by the action of natural forces
  4. a product of accretion
  5. an extraneous addition
    • accretion s of grime

accretion disk -n

  1. a disk of usu. gaseous matter surrounding a massive celestial object (as a black hole) in which the matter gradually spirals in toward and accretes onto the object as a result of gravitational attraction

ac·cru·al [ə-'krü-əl] -n

  1. the action or process of accruing
  2. something that accrues or has accrued

accrual -adj

  1. relating to or being a method of accounting that recognizes income when earned and expenses when incurred regardless of when cash is received or disbursed

ac·crue [ə-'krü] -vb, adj, n

  1. to come into existence as a legally enforceable claim
  2. to come about as a natural growth, increase, or advantage
    • the wisdom that accrue s with age
  3. to come as a direct result of some state or action
    • rewards due to the feminine will accrue to me -- Germaine Greer
  4. to accumulate or be added periodically
    • interest accrue s on a daily basis
  5. to accumulate or have due after a period of time
    • accrue vacation time

acct -abbr

  1. account; accountant

ac·cul·tur·ate [ə-'kəl-chə-,rāt, a-] -vt

  1. to change through acculturation

ac·cul·tur·a·tion [ə-,kəl-chə-'rā-shən, a-] -n, adj

  1. cultural modification of an individual, group, or people by adapting to or borrowing traits from another culture
  2. a merging of cultures as a result of prolonged contact
  3. the process by which a human being acquires the culture of a particular society from infancy

ac·cu·mu·late [ə-'kyü-m(y)ə-,lāt] -vb

  1. to gather or pile up esp. little by little : amass
    • accumulate a fortune
  2. to increase gradually in quantity or number

ac·cu·mu·la·tion [ə-,kyü-m(y)ə-'lā-shən] -n

  1. something that has accumulated or has been accumulated
  2. the action or process of accumulating : the state of being or having accumulated
  3. increase or growth by addition esp. when continuous or repeated
    • accumulation of interest

ac·cu·mu·la·tive [ə-'kyü-m(y)ə-,lā-tiv, -lə-] -adj, adv, n

  1. cumulative
    • an age of rapid and accumulative change
  2. tending or given to accumulation

ac·cu·mu·la·tor [ə-'kyü-m(y)ə-,lā-tər] -n

  1. : one that accumulates: as
  2. a device (as in a hydraulic system) in which a fluid is collected and esp. in which it is kept under pressure as a means of storing energy
  3. storage battery
  4. a part (as in a computer) where numbers are totaled or stored

ac·cu·ra·cy ['a-kyə-rə-sē, 'a-k(ə-)rə-] -n

  1. freedom from mistake or error : correctness
  2. conformity to truth or to a standard or model : exactness
  3. degree of conformity of a measure to a standard or a true value

ac·cu·rate ['a-kyə-rət, 'a-k(ə-)rət] -adj, adv, n

  1. free from error esp. as the result of care
    • an accurate diagnosis
  2. conforming exactly to truth or to a standard : exact
    • providing accurate color
  3. able to give an accurate result
    • an accurate gauge

ac·cursed [ə-'kərst, -'kər-səd] -adj, adv, n

  1. being under or as if under a curse
    • an accursed people
  2. damnable

accus -abbr

  1. accusative

ac·cus·al [ə-'kyü-zəl] -n

  1. accusation

ac·cu·sa·tion [,a-kyə-'zā-shən, -(,)kyü-] -n

  1. the act of accusing : the state or fact of being accused
  2. a charge of wrongdoing

ac·cu·sa·tive [ə-'kyü-zə-tiv] -adj

  1. of, relating to, or being the grammatical case that marks the direct object of a verb or the object of any of several prepositions
  2. accusatory
    • an accusative tone

accusative -n

  1. the accusative case of a language : a form in the accusative case

ac·cu·sa·to·ry [ə-'kyü-zə-,tȯr-ē] -adj

  1. containing or expressing accusation : accusing
    • an accusatory look

ac·cuse [ə-'kyüz] -vb, n, adv

  1. to charge with a fault or offense : blame
  2. to charge with an offense judicially or by a public process
  3. to bring an accusation

ac·cused -n

  1. one charged with an offense
  2. the defendant in a criminal case

ac·cus·tom [ə-'kəs-təm] -vt, n

  1. to make familiar with something through use or experience

ac·cus·tomed [ə-'kəs-təmd] -adj, n

  1. often used or practiced : customary
    • her accustomed cheerfulness
  2. adapted to existing conditions
    • eyes accustomed to the dark
  3. being in the habit or custom
    • accustomed to winning

AC/DC ['ā-(,)sē-'dē-(,)sē] -adj

  1. bisexual

ace ['ās] -n

  1. a die face marked with one spot
  2. a playing card marked in its center with one pip
  3. a domino end marked with one spot
  4. a very small amount or degree : particle
  5. a point scored esp. on a service (as in tennis or handball) that an opponent fails to touch
  6. a golf score of one stroke on a hole
  7. a hole made in one stroke
  8. a combat pilot who has brought down at least five enemy airplanes
  9. a person who excels at something
    • a computer ace
  10. the best pitcher on a baseball team
    • the ace of the staff
  11. to score an ace against (an opponent)
  12. to make (a hole in golf) in one stroke
  13. to gain a decisive advantage over : defeat usu. used with out
  14. to earn a high grade on (as an examination)
  15. to get an A on
  16. to perform extremely well in
    • he aced every subject
  17. of first or high rank or quality
    • an ace mechanic

ACE -abbr

  1. American Council on Education

ace·dia [ə-'sē-dē-ə] -n

  1. apathy, boredom

ACE inhibitor [,ā-(,)sē-'ē-; 'ās-] -n

  1. any of a group of antihypertensive drugs (as captopril) that relax arteries and promote renal excretion of salt and water by inhibiting the activity of angiotensin converting enzyme

Acel·da·ma [ə-'sel-də-mə] -n

  1. the potter's field bought with the money Judas had been paid for betraying Christ

acel·lu·lar [(,)ā-'sel-yə-lər] -adj

  1. containing no cells
    • acellular vaccines
  2. not divided into cells : consisting of a single complex cell used esp. of protozoa and ciliates

acen·tric [(,)ā-'sen-trik] -adj

  1. lacking a centromere
    • acentric chromosomes

aceph·a·lous [(,)ā-'se-fə-ləs, ə-'se-] -adj

  1. lacking a head or having the head reduced
  2. lacking a governing head or chief

ace·quia [ə-'sā-kē-ə, ä-] -n

  1. an irrigation ditch or canal

acerb [ə-'sərb, a-] -adj

  1. acerbic
    • acerb humor

ac·er·bate ['a-sər-,bāt] -vt

  1. irritate, exasperate

acer·bic [ə-'sər-bik, a-] -adj, adv

  1. acid in temper, mood, or tone
    • acerbic commentary
    • an acerbic reviewer

acer·bi·ty [-bə-tē] -n

  1. the quality of being acerbic

ac·er·o·la [,a-sə-'rō-lə] -n

  1. any of various West Indian shrubs (genus Malpighiaof the family Malpighiaceae) with mildly acid cherrylike fruits very rich in vitamin C

ace·sul·fameK ['ā-sē-,səl-,fām-'kā] -n

  1. a white crystalline powder C 4H 4KNO 4S that is a cyclic organic potassium salt, has a sweetness much more intense than sucrose, and is used as a noncaloric sweetener in foods and beverages called also acesulfame potassium

acet- -comb form

  1. acetic acid : acetic
    • acet yl

ac·e·tab·u·lum [-'ta-byə-ləm] -n, adj

  1. a ventral sucker of a trematode
  2. the cup-shaped socket in the hipbone

ac·e·tal ['a-sə-,tal] -n

  1. any of various compounds characterized by the grouping C(OR) 2and obtained esp. by heating aldehydes or ketones with alcohols

ac·et·al·de·hyde [,a-sə-'tal-də-,hīd] -n

  1. a colorless volatile water-soluble liquid aldehyde C 2H 4O used chiefly in organic synthesis

acet·amide [ə-'se-tə-,mīd, ,a-sə-'ta-,mīd] -n

  1. a white crystalline amide C 2H 5NO of acetic acid used esp. as a solvent and in organic synthesis

acet·amin·o·phen [ə-,sē-tə-'mi-nə-fən, ,a-sə-tə-] -n

  1. a crystalline compound C 8H 9NO 2that is a hydroxy derivative of acetanilide and is used in chemical synthesis and in medicine to relieve pain and fever

ac·et·an·i·lide [,a-sə-'ta-nə-,līd, -ləd] -n

  1. a white crystalline compound C 8H 9NO that is derived from aniline and acetic acid and is used esp. to relieve pain or fever

ac·e·tate ['a-sə-,tāt] -n

  1. a salt or ester of acetic acid
  2. cellulose acetate
  3. something (as a textile fiber) made from cellulose acetate
  4. a phonograph recording disk made of an acetate or coated with cellulose acetate

ac·et·azol·amide [,a-sə-tə-'zō-lə-,mīd, -'zä-, -məd] -n

  1. a diuretic drug C 4H 6N 4O 3S 2used esp. in the treatment of edema associated with congestive heart failure and of glaucoma and in the prevention and treatment of altitude sickness

ace·tic acid [ə-'sē-tik-] -n

  1. a colorless pungent liquid acid C 2H 4O 2that is the chief acid of vinegar and that is used esp. in synthesis (as of plastics)

acetic anhydride -n

  1. a colorless liquid C 4H 6O 3with a pungent odor used in organic synthesis (as of cellulose acetate and aspirin)

ace·ti·fy [ə-'sē-tə-,fī, -'se-] -vt, n

  1. to turn into acetic acid or vinegar

ace·to·ace·tic acid [,a-sə-(,)tō-ə-'sē-tik-, ə-,sē-tō-] -n

  1. an unstable acid C 4H 6O 3that is a ketone body found in abnormal quantities in the blood and urine in some conditions (as diabetes)

ac·e·tone ['a-sə-,tōn] -n, adj

  1. a volatile fragrant flammable liquid ketone C 3H 6O used chiefly as a solvent and in organic synthesis and found in abnormal quantities in diabetic urine

ace·to·ni·trile [ə-,sē-tō-'nī-trəl, ,a-sə-tō-, -,trī(-ə)l] -n

  1. the colorless liquid nitrile CH 3CN of acetic acid used chiefly in organic synthesis and as a solvent

ace·to·phe·net·i·din [,a-sə-(,)tō-fə-'ne-tə-dən, ə-,sē-tō-] -n

  1. phenacetin

ace·tous [ə-'sē-təs, 'a-sə-təs] -adj

  1. relating to or producing vinegar
    • acetous fermentation
  2. sour, vinegary

ace·tyl [ə-'sē-tᵊl, 'a-sə-; 'a-sə-,tēl] -n

  1. the radical CH 3CO of acetic acid often used in combination

acet·y·late [ə-'se-tᵊl-,āt] -vt, n, adj

  1. to introduce the acetyl radical into (a compound)

ace·tyl·cho·line [ə-,se-tᵊl-'kō-,lēn, -,sē-; 'a-sə-,tēl-] -n

  1. a neurotransmitter C 7H 17NO 3released at autonomic synapses and neuromuscular junctions and formed enzymatically in the tissues from choline

ace·tyl·cho·lin·es·ter·ase [-,kō-lə-'nes-tə-,rās, -,rāz] -n

  1. an enzyme that occurs esp. in some nerve endings and in the blood and promotes the hydrolysis of acetylcholine

acetyl CoA [-,kō-'ā] -n

  1. acetyl coenzyme a

acetyl coenzyme A -n

  1. a compound C 25H 38N 7O 17P 3S formed as an intermediate in metabolism and active as a coenzyme in biological acetylations

acet·y·lene [ə-'se-tᵊl-ən, -tᵊl-,ēn] -n, adj

  1. a colorless gaseous hydrocarbon HCCH used chiefly in organic synthesis and as a fuel (as in welding and soldering)

ace·tyl·sa·lic·y·late [ə-,sē-tᵊl-sə-'li-sə-,lāt] -n

  1. a salt or ester of acetylsalicylic acid

ace·tyl·sal·i·cyl·ic acid [ə-'sē-tᵊl-,sa-lə-,si-lik-] -n

  1. aspirin

ac·eydeuc·ey [,ā-sē-'dü-sē, -'dyü-] -n

  1. a variation of backgammon in which a throw of a 1-2 wins extra turns

Achae·an [ə-'kē-ən] -adj

  1. of, relating to, or characteristic of Achaea
  2. of or relating to Greece

Achaean -n

  1. a native or inhabitant of Achaea
  2. greek

Ach·ae·me·ni·an [,a-kə-'mē-nē-ən] -adj

  1. of or relating to the Achaemenids

Achae·me·nid [ə-'kē-mə-nəd] -n

  1. a member of the ruling house of ancient Persia generally considered historically important from the assumption of power by Cyrus the Great (559 b.c.) to the overthrow of Darius III (330 b.c.)

acha·la·sia [,ā-kə-'lā-zh(ē-)ə] -n

  1. failure of a ring of muscle (as the anal sphincter or one of the esophagus) to relax

Acha·tes [ə-'kā-tēz] -n

  1. a faithful companion of Aeneas in Virgil's Aeneid

ache ['āk] -vi

  1. to suffer a usu. dull persistent pain
    • an aching back
  2. to become distressed or disturbed (as with anxiety or regret)
    • aching with sadness
  3. to feel compassion
    • my heart ache s for those poor people
  4. to experience a painful eagerness or yearning
    • he is aching to go
  5. a usu. dull persistent pain
  6. a condition marked by aching

achene [ə-'kēn] -n

  1. a small dry indehiscent one-seeded fruit (as of a sunflower) developing from a simple ovary and usu. having a thin pericarp attached to the seed at only one point

Ach·er·on ['a-kə-,rän, -rən] -n

  1. a river in Hades

Acheu·le·an [ə-'shü-lē-ən] -adj

  1. of or relating to a Lower Paleolithic culture originating in Africa and typified by bifacial tools with round cutting edges

achieve [ə-'chēv] -vb, adj, n

  1. to carry out successfully : accomplish
    • achieve a gradual increase in production
  2. to get or attain as the result of exertion : reach
    • achieved a high degree of skill
    • achieved greatness
  3. to attain a desired end or aim : become successful

achieved -adj

  1. brought to or marked by a high degree of development or refinement : finished
    • fully achieved poems

achieve·ment [ə-'chēv-mənt] -n

  1. the act of achieving : accomplishment
  2. a result gained by effort
  3. a great or heroic deed
  4. the quality and quantity of a student's work

Achil·les [ə-'ki-lēz] -n

  1. the greatest warrior among the Greeks at Troy and slayer of Hector

Achilles' heel -n

  1. a vulnerable point

Achilles tendon -n

  1. the strong tendon joining the muscles in the calf of the leg to the bone of the heel called also Achilles

ach·ing ['ā-kiŋ] -adj

  1. that aches
    • an aching back
  2. causing or reflecting distress, deep emotion, or longing
    • aching country ballads

ach·ing·ly [-lē] -adv

  1. in an aching manner
    • achingly sad songs
  2. EXTREMELY, EXCEEDINGLY
    • achingly complicated

achi·o·te [,ä-chē-'ō-tē] -n

  1. a spice made from the red seed of the annatto tree
  2. the seed from which the spice is made

achi·ral [,ā-'kī-rəl] -adj

  1. of, relating to, or being a molecule that is superimposable on its mirror image : not chiral

achlor·hyd·ria [,ā-,klȯr-'hi-drē-ə] -n, adj

  1. absence of hydrochloric acid from the gastric juice

achon·drite [(,)ā-'kän-,drīt] -n, adj

  1. a stony meteorite without rounded grains

achon·dro·pla·sia [,ā-,kän-drə-'plā-zh(ē-)ə] -n, adj

  1. a genetic disorder disturbing normal growth of cartilage, resulting in a form of dwarfism characterized by a usu. normal torso and shortened limbs, and usu. inherited as an autosomal dominant trait

achoo [ä-'chü] -interj

  1. used to represent the sound of a sneeze

ach·ro·mat ['a-krə-,mat] -n

  1. achromatic lens

ach·ro·mat·ic [,a-krə-'ma-tik, (,)ā-] -adj, adv, n, vt

  1. refracting light without dispersing it into its constituent colors : giving images practically free from extraneous colors
    • an achromatic telescope
  2. not readily colored by the usual staining agents
  3. possessing no hue : being or involving black, gray, or white : neutral
    • achromatic visual sensations
  4. being without accidentals or modulation : diatonic

achromatic lens -n

  1. a lens made by combining lenses of different glasses having different focal powers so that the light emerging from the lens forms an image practically free of chromatic aberration

achy ['ā-kē] -adj, n

  1. afflicted with aches
    • feeling tired and achy

acic·u·lar [ə-'si-kyə-lər] -adj

  1. shaped like a needle
    • acicular leaves
    • acicular crystals

ac·id ['a-səd] -adj, adv, n

  1. sour, sharp, or biting to the taste
    • an acid flavor
  2. sharp, biting, or sour in manner, disposition, or nature
    • an acid individual
    • an acid personality
  3. sharply clear, discerning, or pointed
    • an acid wit
    • acid criticism
  4. piercingly intense and often jarring
    • acid yellow
  5. of, relating to, or being an acid
  6. having the reactions or characteristics of an acid
    • acid soil
    • an acid solution
  7. derived by partial exchange of replaceable hydrogen
    • acid sodium carbonate NaHCO 3
  8. containing or involving the use of an acid (as in manufacture)
    • an acid bath
  9. marked by or resulting from an abnormally high concentration of acid
    • acid indigestion
  10. relating to or made by a process (as in making steel) in which the furnace is lined with acidic material and an acidic slag is used
  11. rich in silica
    • acid rocks

acid ['a-sə-dē] -n, adj

  1. a sour substance
  2. any of various typically water-soluble and sour compounds that in solution are capable of reacting with a base to form a salt, redden litmus, and have a pH less than 7, that are hydrogen-containing molecules or ions able to give up a proton to a base, or that are substances able to accept an unshared pair of electrons from a base
  3. something incisive, biting, or sarcastic
    • a social satire dripping with acid
  4. lsd

ac·idfast ['a-səd-,fast] -adj

  1. not easily decolorized by acids

ac·id·head [-,hed] -n

  1. an individual who uses LSD

acid·ic [ə-'si-dik, a-] -adj

  1. acid-forming
  2. acid

acid·i·fi·er [ə-'si-də-,fī(-ə)r, a-] -n

  1. one that acidifies
  2. a substance used to increase soil acidity

acid·i·fy [-,fī] -vt, n

  1. to make acid
  2. to convert into an acid

ac·i·dim·e·ter [,a-sə-'di-mə-tər] -n

  1. ph meter

acid·i·ty [ə-'si-də-tē, a-] -n

  1. the quality, state, or degree of being acid
  2. the state of being excessively acid

acid·o·phil [ə-'si-də-,fil, a-] -n, adj

  1. a substance, tissue, or organism that stains readily with acid stains

ac·i·do·phil·ic [,a-sə-dō-'fi-lik] -adj

  1. staining readily with acid stains : acidophil
  2. preferring or thriving in a relatively acid environment

ac·i·doph·i·lus [,a-sə-'dä-f(ə-)ləs] -n

  1. a lactobacillus ( Lactobacillus acidophilus) that is added esp. to dairy products (as yogurt and milk) or prepared as a dietary supplement, is part of the normal intestinal and vaginal flora, and is used therapeutically esp. to promote intestinal health
  2. a preparation containing such bacteria

ac·i·do·sis [,a-sə-'dō-səs] -n, adj

  1. an abnormal condition characterized by reduced alkalinity of the blood and of the body tissues

acid phosphatase -n

  1. a phosphatase (as the phosphomonoesterase from the prostate gland) optimally active in acid medium

acid precipitation -n

  1. precipitation (as rain or snow) having increased acidity caused by environmental factors (as atmospheric pollutants)

acid rain -n

  1. acid precipitation in the form of rain

acid rock -n

  1. rock music with lyrics and sound relating to or suggestive of drug-induced experiences

acid snow -n

  1. acid precipitation in the form of snow

acid test -n

  1. a severe or crucial test

acid·u·late [ə-'si-jə-,lāt] -vt, n

  1. to make acid or slightly acid

acid·u·lent [ə-'si-jə-lənt] -adj

  1. acidulous

acid·u·lous [ə-'si-jə-ləs] -adj

  1. somewhat acid or harsh in taste or manner

acidwashed ['a-səd-,wȯsht, -,wäsht] -adj

  1. of, relating to, or being a fabric or a garment that has been treated with a bleach solution to produce a streaked or discolored appearance

ac·i·nar ['a-sə-nər, -,när] -adj

  1. of, relating to, or comprising an acinus
    • pancreatic acinar cells

ac·i·nus ['a-sə-nəs] -n, adj

  1. any of the small sacs terminating the ducts of some exocrine glands and lined with secretory cells

ack -abbr

  1. acknowledge; acknowledgment

ackack ['ak-,ak] -n

  1. an antiaircraft gun
  2. antiaircraft fire

ackee ['a-,kē, a-'kē] -n

  1. the fruit of an African tree ( Blighia sapida) of the soapberry family grown in the Caribbean area, Florida, and Hawaii for its white or yellowish fleshy aril that is edible when ripe but is poisonous when immature or overripe and that has a toxic pink raphe attaching the aril to the seed
  2. the tree

ac·knowl·edge [ik-'nä-lij, ak-] -vt

  1. to recognize the rights, authority, or status of
  2. to disclose knowledge of or agreement with
  3. to express gratitude or obligation for
    • acknowledge a gift
  4. to take notice of
    • failed to acknowledge my greeting
  5. to make known the receipt of
    • acknowledge a letter
  6. to recognize as genuine or valid
    • acknowledge a debt

ac·knowl·edged [-lijd] -adj, adv

  1. generally recognized, accepted, or admitted
    • an acknowledged expert

ac·knowl·edg·ment [ik-'nä-lij-mənt, ak-] -n

  1. the act of acknowledging
  2. recognition or favorable notice of an act or achievement
  3. a thing done or given in recognition of something received
  4. a declaration or avowal of one's act or of a fact to give it legal validity

ACL [,ā-(,)sē-'el] -n

  1. anterior cruciate ligament

ACLS -abbr

  1. advanced cardiac life support

ACLU -abbr

  1. American Civil Liberties Union

ac·me ['ak-mē] -n

  1. the highest point or stage
  2. one that represents perfection of the thing expressed

ac·ne ['ak-nē] -n, adj

  1. a disorder of the skin caused by inflammation of the skin glands and hair follicles
  2. a form found chiefly in adolescents and marked by pimples esp. on the face

acne rosacea -n

  1. rosacea

acock [ə-'käk] -adj or adv

  1. being in a cocked position

acoe·lo·mate [(,)ā-'sē-lə-,māt] -n, adj

  1. an invertebrate lacking a coelom
  2. one belonging to the group comprising the flatworms and nemerteans and characterized by bilateral symmetry and a digestive cavity that is the only internal cavity

acold [ə-'kōld] -adj

  1. cold, chilled
    • the owl, for all his feathers, was acold -- John Keats

ac·o·lyte ['a-kə-,līt, -kō-] -n

  1. one who assists a member of the clergy in a liturgical service by performing minor duties
  2. one who attends or assists : follower

ac·o·nite ['a-kə-,nīt] -n

  1. monkshood
  2. the dried poisonous tuberous root of a common monkshood ( Aconitum napellus) used esp. formerly for its medicinal properties (as in relieving pain)

acorn ['ā-,kȯrn, -kərn] -n

  1. the nut of the oak usu. seated in or surrounded by a hard woody cupule of indurated bracts

acorn squash -n

  1. an acorn-shaped dark green winter squash ( Cucurbita pepo) with a ridged surface and mildly sweet yellow to orange flesh

acorn woodpecker -n

  1. a woodpecker ( Melanerpes formicivorus) found from the U.S. Pacific coast south to Colombia that stores acorns in small holes which it digs esp. in the bark of trees

acorn worm -n

  1. any of a class (Enteropneusta) of burrowing wormlike marine animals having an acorn-shaped proboscis and classified with the hemichordates

acous·tic [ə-'küs-tik] -adj, adv

  1. : of or relating to the sense or organs of hearing, to sound, or to the science of sounds
    • acoustic apparatus of the ear
    • acoustic energy
    : as
  2. deadening or absorbing sound
    • acoustic tile
  3. operated by or utilizing sound waves
  4. of, relating to, or being a musical instrument whose sound is not electronically modified

ac·ous·ti·cian [,a-,kü-'sti-shən, ə-,kü-] -n

  1. a specialist in acoustics

acous·tics [ə-'küs-tiks] -n pl

  1. a science that deals with the production, control, transmission, reception, and effects of sound
  2. the qualities that determine the ability of an enclosure (as an auditorium) to reflect sound waves in such a way as to produce distinct hearing

ACP -abbr

  1. African, Caribbean and Pacific (states)
  2. American College of Physicians

acpt -abbr

  1. acceptance

ac·quaint [ə-'kwānt] -vt

  1. to cause to know personally
    • was acquaint ed with the mayor
  2. to make familiar : cause to know firsthand

ac·quain·tance [ə-'kwān-tᵊn(t)s] -n

  1. the state of being acquainted
  2. personal knowledge : familiarity
  3. the persons with whom one is acquainted
    • should auld acquaintance be forgot -- Robert Burns
  4. a person whom one knows but who is not a particularly close friend
    • a casual acquaintance

acquaintance rape -n

  1. rape committed by someone known to the victim

ac·qui·esce [,a-kwē-'es] -vi

  1. to accept, comply, or submit tacitly or passively often used with in and sometimes with to

ac·qui·es·cence [-'e-sᵊn(t)s] -n

  1. the act of acquiescing : the state of being acquiescent
  2. an instance of acquiescing

ac·qui·es·cent [-'e-sᵊnt] -adj, adv

  1. inclined to acquiesce

ac·quir·able [ə-'kwī-rə-bəl] -adj

  1. capable of being acquired

ac·quire [ə-'kwī(-ə)r] -vt

  1. : to get as one's own:
  2. to come into possession or control of often by unspecified means
  3. to come to have as a new or added characteristic, trait, or ability (as by sustained effort or natural selection)
    • acquire fluency in French
    • bacteria that acquire tolerance to antibiotics
  4. to locate and hold (a desired object) in a detector
    • acquire a target by radar

acquired immune deficiency syndrome -n

  1. aids

acquired immunodeficiency syndrome -n

  1. aids

acquired taste -n

  1. something or someone that is not easily or immediately liked or appreciated

ac·quir·ee [ə-,kwī(-ə)-'rē] -n

  1. one (as a company) that is acquired : acquisition

ac·quire·ment [ə-'kwī(-ə)r-mənt] -n

  1. a skill of mind or body usu. resulting from continued endeavor
  2. the act of acquiring

ac·quir·er [ə-'kwī(-ə)r-ər] -n

  1. one that acquires
  2. a company that acquires another company

ac·qui·si·tion [,a-kwə-'zi-shən] -n, adj

  1. the act of acquiring
  2. something or someone acquired or gained
    • the team announced two new acquisition s

ac·quis·i·tive [ə-'kwi-zə-tiv] -adj, adv, n

  1. strongly desirous of acquiring and possessing

ac·quit [ə-'kwit] -vt, n

  1. to pay off (as a claim or debt)
  2. repay, requite
  3. to discharge completely (as from an obligation or accusation)
    • the court acquitted the prisoner
  4. to conduct (oneself) usu. satisfactorily esp. under stress
    • the recruits acquitted themselves like veterans

ac·quit·tal [ə-'kwi-tᵊl] -n

  1. a setting free from the charge of an offense by verdict, sentence, or other legal process

ac·quit·tance [ə-'kwi-tᵊn(t)s] -n

  1. a document evidencing a discharge from an obligation
  2. a receipt in full

acr- -comb form

  1. beginning : end : tip
    • acr onym
  2. top : peak : summit
    • acro petal
  3. height
    • acro phobia

acre ['ā-kər] -n

  1. a field esp. of arable land or pastureland
  2. lands, estate
  3. any of various units of area
  4. a unit in the U.S. and England equal to 43,560 square feet (4047 square meters)
  5. a broad expanse or great quantity
    • acre s of free publicity

acre·age ['ā-k(ə-)rij] -n

  1. area in acres : acres

acrefoot ['ā-kər-'fu̇t] -n

  1. the volume (as of irrigation water) that would cover one acre to a depth of one foot

acreinch ['ā-kər-'inch] -n

  1. one twelfth of an acre-foot

ac·rid ['a-krəd] -adj, n, adv

  1. sharp and harsh or unpleasantly pungent in taste or odor : irritating
  2. deeply or violently bitter : acrimonious
    • an acrid denunciation

ac·ri·dine ['a-krə-,dēn] -n

  1. a colorless crystalline compound C 13H 9N occurring in coal tar and important as the parent compound of dyes and pharmaceuticals

acridine orange -n

  1. a basic orange dye structurally related to acridine and used esp. to stain nucleic acids

ac·ri·fla·vine [,a-krə-'flā-,vēn, -vən] -n

  1. a yellow dye C 14H 14N 3Cl used as an antiseptic esp. for wounds

ac·ri·mo·ni·ous [,a-krə-'mō-nē-əs] -adj, adv, n

  1. caustic, biting, or rancorous esp. in feeling, language, or manner
    • an acrimonious dispute

ac·ri·mo·ny ['a-krə-,mō-nē] -n

  1. harsh or biting sharpness esp. of words, manner, or disposition

ac·ri·tarch ['a-kri-,tärk] -n

  1. any of a group of fossil one-celled marine planktonic organisms of uncertain and possibly various taxonomic affinities held to represent the earliest known eukaryotes

ac·ro·bat ['a-krə-,bat] -n, adj, adv

  1. one that performs gymnastic feats requiring skillful control of the body
  2. one skillful at exercises of intellectual or artistic dexterity
  3. one adept at swiftly changing or adapting a position or viewpoint
    • a political acrobat

ac·ro·bat·ics [,a-krə-'ba-tiks] -n pl but sing or pl in constr

  1. the art, performance, or activity of an acrobat
  2. a spectacular, showy, or startling performance or demonstration involving great agility or complexity

ac·ro·cen·tric [,a-krō-'sen-trik] -adj, n

  1. having the centromere situated so that one chromosomal arm is much shorter than the other

ac·ro·lect ['a-krə-,lekt] -n

  1. the language variety of a speech community closest to the standard or prestige form of a language

acro·le·in [ə-'krō-lē-ən] -n

  1. a colorless irritant pungent liquid aldehyde C 3H 4O used chiefly in organic synthesis

ac·ro·meg·a·ly [,a-krō-'me-gə-lē] -n, adj or n

  1. a disorder caused by excessive production of growth hormone by the pituitary gland and marked esp. by progressive enlargement of hands, feet, and face

ac·ro·nym ['a-krə-,nim] -n, adj, adv

  1. a word (as NATO, radar,or laser) formed from the initial letter or letters of each of the successive parts or major parts of a compound term
  2. an abbreviation (as FBI) formed from initial letters : initialism

acrop·e·tal [ə-'krä-pə-tᵊl, a-] -adj, adv

  1. proceeding from the base toward the apex or from below upward
    • acropetal development of floral buds

ac·ro·pho·bia [,a-krə-'fō-bē-ə] -n, adj

  1. abnormal dread of being in a high place : fear of heights

acrop·o·lis [ə-'krä-pə-ləs] -n

  1. the upper fortified part of an ancient Greek city (as Athens)
  2. a usu. fortified height of a city or district elsewhere (as in Central America)

ac·ro·some ['a-krə-,sōm] -n, adj

  1. an anterior prolongation of a spermatozoon that releases egg-penetrating enzymes

across [ə-'krȯs, chiefly dial -'krȯst] -adv

  1. in a position reaching from one side to the other : crosswise
  2. to or on the opposite side
  3. so as to be understandable, acceptable, or successful
    • get an argument across
  4. being in a crossed position
  5. from one side to the opposite side of : over, through
    • swam across the river
  6. on the opposite side of
    • lives across the street from us
  7. so as to intersect or pass through at an angle
    • sawed across the grain of the wood
  8. so as to find or meet
    • came across your football in the hall closet
  9. throughout
    • obvious interest across the nation -- Robert Goralski
  10. so as to include or take into consideration all classes or categories
    • across differences, they insist, there can be no rational dialogue -- Huston Smith

acrosstheboard -adj

  1. placed to win if a competitor wins, places, or shows
    • an acrosstheboard racing bet
  2. embracing or affecting all classes or categories : blanket
    • an acrosstheboard price increase

acros·tic [ə-'krȯs-tik, -'kräs-] -n, adj, adv

  1. a composition usu. in verse in which sets of letters (as the initial or final letters of the lines) taken in order form a word or phrase or a regular sequence of letters of the alphabet
  2. acronym

ac·ryl·am·ide [,a-krəl-'a-,mīd, ə-'kri-lə-] -n

  1. an amide C 3H 5NO that is derived from acrylic acid, that polymerizes readily, and that is used in the manufacture of synthetic textile fibers

ac·ry·late ['a-krə-,lāt] -n

  1. a salt or ester of acrylic acid
  2. acrylic resin

acryl·ic [ə-'kri-lik] -adj

  1. of or relating to acrylic acid or its derivatives
    • acrylic polymers
  2. made or consisting of an acrylic
    • an acrylic window

acrylic -n

  1. acrylic resin
  2. a paint in which the vehicle is an acrylic resin
  3. a painting done in an acrylic resin
  4. acrylic fiber

acrylic acid -n

  1. an unsaturated liquid acid C 3H 4O 2that polymerizes readily to form useful products (as constituents for varnishes and lacquers)

acrylic fiber -n

  1. a quick-drying synthetic textile fiber made by polymerization of acrylonitrile usu. with other monomers

acrylic resin -n

  1. a glassy thermoplastic made by polymerizing acrylic acid or methacrylic acid or a derivative of either and used for cast and molded parts or as coatings and adhesives

ac·ry·lo·ni·trile [,a-krə-lō-'nī-trəl, -,trēl] -n

  1. a colorless volatile flammable liquid nitrile C 3H 3N used chiefly in organic synthesis and for polymerization

ACS -abbr

  1. American Chemical Society
  2. American College of Surgeons

act ['akt] -n

  1. the doing of a thing : deed
  2. something done voluntarily
  3. a state of real existence rather than possibility
  4. the formal product of a legislative body : statute
  5. a decision or determination of a sovereign, a legislative council, or a court of justice
  6. the process of doing : action
    • caught in the act
  7. a formal record of something done or transacted
  8. one of the principal divisions of a theatrical work (as a play or opera)
  9. one of successive parts or performances (as in a variety show or circus)
  10. the performer or performers in such an act
  11. a performance or presentation identified with a particular individual or group
  12. the sum of a person's actions or effects that serve to create an impression or set an example
    • a hard act to follow
  13. a display of affected behavior : pretense
  14. actuate, animate
  15. to represent or perform by action esp. on the stage
  16. feign, simulate
  17. impersonate
  18. to play the part of as if in a play
    • act the man of the world
  19. to behave in a manner suitable to
    • act your age
  20. to perform on the stage
  21. to behave as if performing on the stage : pretend
  22. to take action : move
    • think before act ing
    • act ed favorably on the recommendation
  23. to conduct oneself : behave
    • act like a fool
  24. to perform a specified function : serve
    • trees act ing as a windbreak
  25. to produce an effect : work
    • wait for a medicine to act
  26. to be capable of being performed
    • the play act s well
  27. to give a decision or award
    • adjourned without act ing on the bill
  28. active
  29. actor
  30. actual

ACT -abbr

  1. Action for Children's Television
  2. Association of Classroom Teachers
  3. Australian Capital Territory
  4. used for a standardized achievement test to evaluate suitability for college admission

Ac·tae·on [ak-'tē-ən] -n

  1. a hunter turned into a stag and killed by his own hounds for having seen Artemis bathing

actg -abbr

  1. acting

ACTH [,ā-(,)sē-(,)tē-'āch] -n

  1. a protein hormone of the anterior lobe of the pituitary gland that stimulates the adrenal cortex called also adrenocorticotropic hormone

ac·tin ['ak-tən] -n

  1. a cellular protein found esp. in microfilaments (as those comprising myofibrils) and active in muscular contraction, cellular movement, and maintenance of cell shape

actin- -comb form

  1. having a radiate form
    • actino lite
  2. actinic radiation (as X rays)
    • actino meter

act·ing ['ak-tiŋ] -n

  1. the art or practice of representing a character on a stage or before cameras

acting -adj

  1. holding a temporary rank or position : performing services temporarily
    • acting president
  2. suitable for stage performance
    • an acting play
  3. prepared with directions for actors
    • an acting text of a play

ac·tin·i·an [ak-'ti-nē-ən] -n

  1. sea anemone

ac·tin·ic [ak-'ti-nik] -adj, adv

  1. of, relating to, resulting from, or exhibiting chemical changes produced by radiant energy esp. in the visible and ultraviolet parts of the spectrum
    • actinic light
    • actinic keratosis

ac·ti·nide ['ak-tə-,nīd] -n

  1. any of the series of elements with increasing atomic numbers that begins with actinium or thorium and ends with lawrencium

ac·tin·i·um [ak-'ti-nē-əm] -n

  1. a radioactive trivalent metallic element that resembles lanthanum in chemical properties and that is found esp. in pitchblende

ac·tin·o·lite [ak-'ti-nə-,līt] -n

  1. a bright green or grayish-green mineral of the amphibole group that is a silicate of calcium, magnesium, and iron occurring in fibrous, radiate, or columnar forms

ac·ti·nom·e·ter [,ak-tə-'nä-mə-tər] -n, adj

  1. any of various instruments for measuring the intensity of incident radiation
  2. one in which the intensity of radiation is measured by the speed of a photochemical reaction

ac·ti·no·mor·phic [,ak-(,)ti-nō-'mȯr-fik, -tə-nō-; ak-,ti-nō-] -adj, n

  1. being radially symmetrical and capable of division by any longitudinal plane into essentially symmetrical halves
    • an actinomorphic tulip flower

ac·ti·no·my·ces [,ak-(,)ti-nō-'mī-,sēz, -tə-nō-; ak-,ti-nō-] -n

  1. any of a genus ( Actinomyces) of filamentous or rod-shaped bacteria that includes usu. commensal and sometimes pathogenic forms inhabiting mucosal surfaces esp. of the oral cavity of warm-blooded vertebrates

ac·ti·no·my·cete [-'mī-,sēt, -mī-'sēt] -n

  1. any of an order (Actinomycetales) of filamentous or rod-shaped bacteria (as the actinomyces and streptomyces)

ac·ti·no·my·cin [-'mī-sᵊn] -n

  1. any of various red or yellow-red mostly toxic polypeptide antibiotics isolated from soil bacteria (esp. Streptomyces antibioticus)
  2. one used to inhibit DNA or RNA synthesis

ac·ti·no·my·co·sis [-mī-'kō-səs] -n, adj

  1. infection with or disease caused by actinomyces
  2. a chronic disease of cattle, swine, and humans characterized by hard granulomatous masses usu. in the mouth and jaw

ac·tion ['ak-shən] -n

  1. the initiating of a proceeding in a court of justice by which one demands or enforces one's right
  2. the proceeding itself
  3. the bringing about of an alteration by force or through a natural agency
  4. : the manner or method of performing:
  5. an actor's or speaker's deportment or expression by means of attitude, voice, and gesture
  6. the style of movement of the feet and legs (as of a horse)
  7. a function of the body or one of its parts
  8. an act of will
  9. a thing done : deed
  10. the accomplishment of a thing usu. over a period of time, in stages, or with the possibility of repetition
  11. behavior, conduct
    • unscrupulous action s
  12. initiative, enterprise
    • a man of action
  13. an engagement between troops or ships
  14. combat in war
    • gallantry in action
  15. an event or series of events forming a literary composition
  16. the unfolding of the events of a drama or work of fiction : plot
  17. the movement of incidents in a plot
  18. the combination of circumstances that constitute the subject matter of a painting or sculpture
  19. an operating mechanism
  20. the manner in which a mechanism or instrument operates
  21. the price movement and trading volume of a commodity, security, or market
  22. the process of betting including the offering and acceptance of a bet and determination of a winner
  23. financial gain or an opportunity for financial gain
    • a piece of the action
  24. sexual activity
  25. the most vigorous, productive, or exciting activity in a particular field, area, or group
    • wants to be where the action is

ac·tion·able ['ak-sh(ə-)nə-bəl] -adj, adv

  1. subject to or affording ground for an action or suit at law
  2. capable of being acted on
    • actionable information

ac·tion·er ['ak-sh(ə-)nər] -n

  1. a film dominated by a high degree of exciting action

action figure -n

  1. a small-scale figure (as of a superhero) used esp. as a toy

ac·tion·less ['ak-shən-ləs] -adj

  1. marked by inaction : immobile

action painting -n

  1. abstract expressionism marked esp. by the use of spontaneous techniques (as dribbling, splattering, or smearing)

action potential -n

  1. a momentary reversal in electrical potential across a plasma membrane (as of a neuron or muscle fiber) that occurs when a cell has been activated by a stimulus

ac·ti·vate ['ak-tə-,vāt] -vb, n

  1. : to make active or more active: as
  2. to make (as molecules) reactive or more reactive
  3. to convert (as a provitamin) into a biologically active derivative
  4. to make (a substance) radioactive
  5. to treat (as carbon or alumina) so as to improve adsorptive properties
  6. to set up or formally institute (as a military unit) with the necessary personnel and equipment
  7. to put (an individual or unit) on active duty
  8. to become active

activated carbon -n

  1. a highly adsorbent powdered or granular carbon made usu. by carbonization and chemical activation and used chiefly for purifying by adsorption called also activated charcoal

activation analysis -n

  1. neutron activation analysis

activation energy -n

  1. the minimum amount of energy required to convert a normal stable molecule into a reactive molecule

ac·tive ['ak-tiv] -adj, n, adv

  1. characterized by action rather than by contemplation or speculation
    • an active life
  2. producing or involving action or movement
  3. asserting that the person or thing represented by the grammatical subject performs the action represented by the verb
    • hits in he hits the ball is active
  4. expressing action as distinct from mere existence or state
  5. quick in physical movement : lively
  6. marked by vigorous activity : busy
    • the stock market was active
  7. requiring vigorous action or exertion
    • active sports
  8. having practical operation or results : effective
    • an active law
  9. disposed to action : energetic
    • took an active interest
  10. engaged in an action or activity
    • an active club member
  11. currently erupting or likely to erupt
  12. characterized by emission of large amounts of electromagnetic energy
    • an active galactic nucleus
  13. engaged in full-time service esp. in the armed forces
    • active duty
  14. marked by present operation, transaction, movement, or use
    • an active account
  15. capable of acting or reacting : reacting readily
    • active nitrogen
    • active ingredients
  16. tending to progress or to cause degeneration
    • active tuberculosis
  17. capable of controlling voltages or currents
  18. requiring the expenditure of energy
    • active calcium ion uptake
  19. functioning by the emission of radiant energy or sound
    • radar is an active sensor
  20. still eligible to win the pot in poker
  21. moving down the line : visiting in the set used of couples in contredanses or square dances

active immunity -n

  1. usu. long-lasting immunity that is acquired through production of antibodies within the organism in response to the presence of antigens

ac·tivema·trix ['ak-tiv-,mā-triks] -adj

  1. of, relating to, or being an LCD in which each pixel is individually controlled

active site -n

  1. a region on the surface of an enzyme whose shape permits binding only of a specific molecular substrate that then undergoes catalysis

active transport -n

  1. the movement of a chemical substance by the expenditure of energy against a gradient in concentration or in electrical potential across a plasma membrane

ac·tive·wear ['ak-tiv-,wer] -n

  1. SPORTSWEAR

ac·tiv·ism ['ak-ti-,vi-zəm] -n, n or adj, adj

  1. a doctrine or practice that emphasizes direct vigorous action esp. in support of or opposition to one side of a controversial issue

ac·tiv·i·ty [ak-'ti-və-tē] -n

  1. the quality or state of being active
  2. vigorous or energetic action : liveliness
  3. : natural or normal function: as
  4. a process (as digestion) that an organism carries on or participates in by virtue of being alive
  5. a similar process actually or potentially involving mental function
  6. an educational procedure designed to stimulate learning by firsthand experience
  7. an active force
  8. a pursuit in which a person is active
  9. a form of organized, supervised, often extracurricular recreation
  10. an organizational unit for performing a specific function
  11. its function or duties

act of God

  1. an extraordinary interruption by a natural cause (as a flood or earthquake) of the usual course of events that experience, prescience, or care cannot reasonably foresee or prevent

ac·to·my·o·sin [,ak-tə-'mī-ə-sən] -n

  1. a contractile complex of actin and myosin that together with ATP is active during muscular contraction

ac·tor ['ak-tər also -,tȯr] -n, adj

  1. one that acts : doer
  2. one who represents a character in a dramatic production
  3. a theatrical performer
  4. one who behaves as if acting a part
  5. one that takes part in any affair

act out -vt

  1. to represent in action
    • children act out what they read
  2. to translate into action
    • unwilling to act out their beliefs
  3. to express (as an impulse or a fantasy) directly in overt behavior without modification to comply with social norms
  4. to behave badly or in a socially unacceptable often self-defeating manner esp. as a means of venting painful emotions (as fear or frustration)

ac·tress ['ak-trəs] -n, adj

  1. a woman who is an actor

Acts ['akts] -n pl but sing in constr

  1. a book in the New Testament narrating the beginnings of the Christian church called also Acts of the Apostles

ac·tu·al ['ak-ch(ə-w)əl, -sh(ə-w)əl; -chü-əl, -shü-] -adj

  1. active
  2. existing in act and not merely potentially
  3. existing in fact or reality
    • actual and imagined conditions
  4. not false or apparent
    • actual costs
  5. existing or occurring at the time : current
    • caught in the actual commission of a crime

actual cash value -n

  1. money equal to the cost of replacing lost, stolen, or damaged property after depreciation

ac·tu·al·i·ty [,ak-chə-'wa-lə-tē, ,ak-shə-] -n

  1. the quality or state of being actual
  2. something that is actual : fact, reality
    • possible risks which have been seized upon as actualities -- T. S. Eliot

ac·tu·al·ize ['ak-ch(ə-w)ə-,līz, -sh(ə-w)ə-,līz] -vb, n

  1. to make actual : realize
  2. to become actual

ac·tu·al·ly ['ak-ch(ə-w)ə-lē, -sh(ə-w)ə-lē; 'aksh-lē, 'aks-] -adv

  1. in act or in fact : really
    • nominally but not actually independent -- Karl Loewenstein
    • won't actually arrive for an hour
  2. in point of fact used to suggest something unexpected
    • he could actually read the Greek

ac·tu·ar·i·al [,ak-chə-'wer-ē-əl, -'wer-rē-, -shə-] -adj, adv

  1. of or relating to actuaries
  2. relating to statistical calculation esp. of life expectancy

ac·tu·ary ['ak-chə-,wer-ē, -shə-, -,we-rē-] -n

  1. clerk, registrar
  2. a person who calculates insurance and annuity premiums, reserves, and dividends

ac·tu·ate ['ak-chə-,wāt, -shə-] -vt, n

  1. to put into mechanical action or motion
  2. to move to action

ac·tu·a·tor ['ak-chə-,wā-tər, -shə-] -n

  1. one that actuates
  2. a mechanical device for moving or controlling something

act up -vi

  1. : to act in a way different from that which is normal or expected: as
  2. to behave in an unruly, recalcitrant, or capricious manner
    • the children were acting up
  3. show off
  4. to function improperly
    • this typewriter is acting up again
  5. to become active or acute after being quiescent
    • her rheumatism started to act up

ACT UP -abbr

  1. AIDS Coalition to Unleash Power

acu·ity [ə-'kyü-ə-tē, a-] -n

  1. keenness of perception : sharpness

acu·le·ate [ə-'kyü-lē-ət] -adj

  1. relating to or being hymenopterans (as bees, ants, and many wasps) of a division (Aculeata) typically having the ovipositor modified into a stinger

acu·men [ə-'kyü-mən, 'a-kyə-mən] -n

  1. keenness and depth of perception, discernment, or discrimination esp. in practical matters

acu·mi·nate [ə-'kyü-mə-nət] -adj

  1. tapering to a slender point

acu·pres·sure ['a-kyə-,pre-shər, 'a-kə-] -n

  1. the application of pressure (as with the thumbs or fingertips) to the same discrete points on the body stimulated in acupuncture that is used for its therapeutic effects (as the relief of tension or pain)

acu·punc·ture [-,pəŋ(k)-chər] -n, vt

  1. an orig. Chinese practice of inserting fine needles through the skin at specific points esp. to cure disease or relieve pain (as in surgery)

acute [ə-'kyüt] -adj, adv, n

  1. characterized by sharpness or severity
    • acute pain
  2. having a sudden onset, sharp rise, and short course
    • acute disease
  3. being, providing, or requiring short-term medical care (as for serious illness or traumatic injury)
    • acute hospitals
    • an acute patient
  4. lasting a short time
    • acute experiments
  5. : ending in a sharp point: as
  6. being or forming an angle measuring less than 90 degrees
    • an acute angle
  7. composed of acute angles
    • an acute triangle
  8. having the form
  9. marked with an acute accent
  10. of the variety indicated by an acute accent
  11. marked by keen discernment or intellectual perception esp. of subtle distinctions : penetrating
    • an acute thinker
  12. responsive to slight impressions or stimuli
    • acute hearing
  13. felt, perceived, or experienced intensely
    • acute distress
  14. seriously demanding urgent attention
    • an acute emergency

ACV -abbr

  1. actual cash value
  2. air-cushion vehicle

acy·clic [(,)ā-'sī-klik, -'si-] -adj

  1. : not cyclic: as
  2. not disposed in whorls or cycles
  3. having an open-chain structure : aliphatic
    • an acyclic compound

acy·clo·vir [(,)ā-'sī-klō-,vir] -n

  1. a cyclic synthetic nucleoside C 8H 11N 5O 3used esp. to treat the symptoms of chicken pox, shingles, and the genital form of herpes simplex

ac·yl ['a-səl] -n

  1. a radical RCO derived usu. from an organic acid by removal of the hydroxyl from all acid groups often used in combination

ac·yl·ate ['a-sə-,lāt] -vt, n

  1. to introduce an acyl radical into