on ['ȯn, 'än] -prep

  1. used as a function word to indicate position in contact with and supported by the top surface of
    • the book is lying on the table
  2. used as a function word to indicate position in or in contact with an outer surface
    • the fly landed on the ceiling
    • I have a cut on my finger
    • paint on the wall
  3. used as a function word to indicate position in close proximity with
    • a village on the sea
    • stay on your opponent
  4. used as a function word to indicate the location of something
    • on the left
    • on the south side of the house
    • on the farm
  5. used as a function word to indicate a source of attachment or support
    • on a string
    • stand on one foot
    • hang it on a nail
  6. used as a function word to indicate a source of dependence
    • you can rely on me
    • feeds on insects
    • lives on a pension
  7. used as a function word to indicate means of conveyance
    • on the bus
  8. used as a function word to indicate presence in the possession of
    • had a knife on him
  9. used as a function word to indicate a time frame during which something takes place
    • a parade on Sunday
    or an instant, action, or occurrence when something begins or is done
    • on cue
    • on arriving home, I found your letter
    • news on the hour
    • cash on delivery
  10. of
  11. used as a function word to indicate manner of doing something often used with the
    • on the sly
    • keep everything on the up-and-up
  12. used as a function word to indicate means or agency
    • cut myself on a knife
    • talk on the telephone
  13. used as a function word to indicate a medium of expression
    • on stage
    • best show on television
  14. used as a function word to indicate active involvement in a condition or status
    • on the increase
    • on the lookout
  15. regularly using or showing the effects of using
    • on drugs
  16. used as a function word to indicate involvement or participation
    • on tour
    • on the team
    • on duty
  17. used as a function word to indicate inclusion
    • put it on the agenda
  18. used as a function word to indicate position or status in proper relationship with a standard or objective
    • on schedule
  19. used as a function word to indicate reason, ground, or basis (as for an action, opinion, or computation)
    • I have it on good authority
    • on one condition
    • the interest will be 10 cents on the dollar
  20. used as a function word to indicate the cause or source
    • profited on the sale of stock
  21. used as a function word to indicate the focus of obligation or responsibility
    • drinks are on the house
    • put the blame on me
  22. used as a function word to indicate the object of collision, opposition, or hostile action
    • bumped my head on a limb
    • an attack on religion
    • pulled a gun on me
  23. used as a function word to indicate the object with respect to some disadvantage, handicap, or detriment
    • has three inches in height on me
    • a 3-game lead on the second-place team
    • the joke's on me
  24. used as a function word to indicate destination or the focus of some action, movement, or directed effort
    • crept up on him
    • feast your eyes on this
    • working on my skiing
    • made a payment on the loan
  25. used as a function word to indicate the focus of feelings, determination, or will
    • have pity on me
    • keen on sports
    • a curse on you
  26. used as a function word to indicate the object with respect to some misfortune or disadvantageous event
    • the crops died on them
  27. used as a function word to indicate the subject of study, discussion, or consideration
    • a book on insects
    • reflect on that a moment
    • agree on price
  28. with respect to
    • go light on the salt
    • short on cash
  29. used as a function word to indicate reduplication or succession in a series
    • loss on loss
  30. in or into a position of contact with an upper surface esp. so as to be positioned for use or operation
    • put the plates on
  31. in or into a position of being attached to or covering a surface
  32. in or into the condition of being worn
    • put his new shoes on
  33. forward or at a more advanced point in space or time
    • went on home
    • later on
  34. in continuance or succession
    • rambled on
    • and so on
  35. into operation or a position permitting operation
    • switched the light on
  36. engaged in an activity or function (as a dramatic role)
  37. being in operation
    • the radio is on
  38. placed so as to permit operation
    • the switch is on
  39. taking place or being broadcast
    • the game is on
  40. aware of something usu. used with to
    • my boss was on to me
  41. intended, planned
    • has nothing on for tonight
  42. talking or harping incessantly used with about
  43. regarded as possible or feasible usu. used in negative constructions
  44. engaged in or as if in a performance
    • the comedian was always on
  45. being at a high level of performance

ON -abbr

  1. Ontario

onagain, offagain -adj

  1. existing briefly and in an intermittent unpredictable way
    • on-again, off-again fads

on·a·ger ['ä-ni-jər] -n

  1. an Asian wild ass ( Equus hemionus onagersyn. E. onager) that usu. has a broad dorsal stripe and is related to the kiang
  2. a heavy catapult used in ancient and medieval times

on and off -adv, adj

  1. off and on

onan·ism ['ō-nə-,ni-zəm] -n, adj

  1. masturbation
  2. coitus interruptus
  3. self-gratification

on·board ['ȯn-'bȯrd, 'än-] -adj

  1. carried within or occurring aboard a vehicle (as a satellite or an automobile)
    • an onboard computer

once ['wən(t)s] -adv

  1. one time and no more
    • rode a horse only once
  2. at any one time : under any circumstances : ever
    • didn't once thank me
  3. at some indefinite time in the past : formerly
    • was once a booming mining town
  4. by one degree of relationship
    • first cousin once removed
  5. one single time : one time at least
    • please be on time this once
  6. that once was : former
    • a once successful actor
  7. at the moment when : as soon as
    • once she spoke, I recognized her

onceover [,wən(t)s-'ō-vər, 'wən(t)s-,] -n

  1. a swift examination or survey
  2. a swift comprehensive appraising glance
    • gave me the onceover

once that -conj

  1. once

on·cho·cer·ci·a·sis [,äŋ-kō-,sər-'kī-ə-səs] -n

  1. infestation with or disease caused by filarial worms (genus Onchocerca)
  2. a human disease marked by subcutaneous nodules, dermatitis, and visual impairment and caused by a worm ( O. volvulus) found in Africa and tropical America which is transmitted by the bite of a female blackfly called also river blindness

on·cid·i·um [än-'si-dē-əm, äŋ-'ki-] -n

  1. any of a genus ( Oncidium) of showy tropical American chiefly epiphytic orchids

onco- -comb form

  1. tumor
    • onco logy

on·co·gene ['äŋ-kō-,jēn] -n

  1. a gene having the potential to cause a normal cell to become cancerous

on·co·gen·e·sis [,äŋ-kō-'je-nə-səs] -n

  1. the induction or formation of tumors

on·co·gen·ic [-'je-nik] -adj, n

  1. relating to tumor formation
  2. tending to cause tumors

on·col·o·gy [än-'kä-lə-jē, äŋ-] -n, adj

  1. the study of tumors

on·com·ing ['ȯn-,kə-miŋ, 'än-] -adj

  1. coming nearer in time or space
    • the oncoming year
    • an oncoming car
  2. future
    • looked forward to his oncoming visit
  3. emergent, rising
    • the oncoming generation

one ['wən] -adj

  1. being a single unit or thing
    • one day at a time
  2. being one in particular
    • early one morning
  3. being preeminently what is indicated
    • one fine person
  4. being the same in kind or quality
    • both of one species
  5. constituting a unified entity of two or more components
    • the combined elements form one substance
  6. being in agreement or union
    • am one with you on this
  7. some
    • will see you again one day
  8. being a certain individual specified by name
    • one John Doe made a speech
  9. only
    • the one person she wanted to marry
  10. the number denoting unity
  11. the first in a set or series often used with an attributive noun
    • day one
  12. an article of clothing of a size designated one
    • wears a one
  13. a single person or thing
    • has the one but needs the other
  14. a one-dollar bill
  15. a certain indefinitely indicated person or thing
    • saw one of his friends
  16. an individual of a vaguely indicated group : anyone at all
    • one never knows
  17. used as a third person substitute for a first person pronoun
    • I'd like to read more but one doesn't have the time
  18. a single instance of a specified action
    • felt like belting him one -- John Casey

one another -pron

  1. each other

onearmed bandit ['wən-'ärm(d)-] -n

  1. slot machine

onebag·ger [-'ba-gər] -n

  1. single

onedimensional -adj, n

  1. having one dimension
  2. lacking depth : superficial
    • onedimensional characters

one·fold ['wən-,fōld, -'fōld] -adj

  1. constituting a single undivided whole

onehand·ed [-'han-dəd] -adj

  1. having or using only one hand
    • could beat him up onehanded
  2. designed for or requiring the use of only one hand
  3. effected by the use of only one hand

onehorse [-'hȯrs] -adj

  1. drawn or operated by one horse
  2. small, small-time
    • a onehorse town

Onei·da [ō-'nī-də] -n

  1. a member of an American Indian people orig. of New York
  2. the Iroquoian language of the Oneida people

onei·ric [ō-'nī-rik] -adj, adv

  1. of or relating to dreams : dreamy

onei·ro·man·cy [ō-'nī-rə-,man(t)-sē] -n

  1. divination by means of dreams

onelin·er [,wən-'lī-nər] -n

  1. a very succinct joke or witticism
  2. a succinct or meaningful and esp. accurate statement

oneman -adj

  1. : of or relating to just one individual: as
  2. consisting of only one individual
    • a oneman committee
  3. done, presented, or produced by only one individual
    • a oneman stage play
  4. featuring the work of a single artist (as a painter)
    • a oneman show of oils
  5. designed for or limited to one individual

oneman band -n

  1. a musician who plays several instruments during a solo performance
  2. a person who alone undertakes or is responsible for several tasks

one·ness ['wən-nəs] -n

  1. : the quality or state or fact of being one: as
  2. singleness
  3. integrity, wholeness
  4. harmony
  5. sameness, identity
  6. unity, union

onenight·er [,wən-'nī-tər] -n

  1. one-night stand

onenight stand -n

  1. a performance (as of a play or concert) given (as by a traveling group of actors or musicians) only once in each of a series of localities
  2. a locality used for one-night stands
  3. a stopover for a one-night stand
  4. a sexual encounter limited to a single occasion
  5. a partner in such an encounter

onenote ['wən-'nōt] -adj

  1. unvarying in tone or emphasis : monotonous
    • a onenote campaigner

oneoff [,wən-'ȯf] -adj, n

  1. limited to a single time, occasion, or instance : one-shot
    • oneoff gigs
  2. singular, unique
    • a oneoff design

oneonone [,wən-ȯn-'wən, ,wən-än-] -adj or adv

  1. playing directly against a single opposing player
  2. involving a direct encounter between one person and another

onepiece ['wən-'pē-sər] -adj, n

  1. consisting of or made in a single undivided piece
    • a onepiece bathing suit

oner·ous ['ä-nə-rəs, 'ō-] -adj, adv, n

  1. involving, imposing, or constituting a burden : troublesome
    • an onerous task
  2. having legal obligations that outweigh the advantages
    • an onerous contract

one·self [(,)wən-'self, Southern also -'sef] -pron

  1. a person's self : one's own self used reflexively as object of a preposition or verb or for emphasis in various constructions
  2. one's normal, healthy, or sane condition or self

oneshot ['wən-,shät] -adj, n

  1. that is complete or effective through being done or used or applied only once
    • there is no easy oneshot answer to the problem
  2. that is not followed by something else of the same kind
    • a oneshot tax cut

onesid·ed ['wən-'sī-dəd] -adj, adv, n

  1. having one side prominent : lopsided
  2. having or occurring on one side only
  3. limited to one side : partial
    • a onesided interpretation
  4. unilateral
    • a onesided decision

ones place -n

  1. units place

onestep ['wən-,step] -n, vi

  1. a ballroom dance in time marked by quick walking steps backward and forward
  2. music used for the one-step

onestop [-'stäp] -adj

  1. providing or offering a comprehensive range of goods or services at one location
  2. provided or offered at such a location
    • onestop shopping

onetailed ['wən-'tāl(d)] -adj

  1. being a statistical test for which the critical region consists of all values of the test statistic greater than a given value or less than a given value but not both

one·time ['wən-'tīm] -adj

  1. former, sometime
    • a onetime actor
  2. occurring only once : one-shot

onetime -adv

  1. formerly

onetoone [,wən-tə-'wən, -də-] -adj

  1. pairing each element of a set uniquely with an element of another set
  2. one-on-one

onetrack -adj

  1. marked by often narrowly restricted attention to or absorption in just one thing
    • a onetrack mind

onetrick pony -n

  1. one that is skilled in only one area
  2. one that has success only once

onetwo ['wən-'tü, -,tü] -n

  1. a combination of two quick blows in rapid succession in boxing
  2. a left jab followed at once by a hard blow with the right hand
  3. two forces combining to produce a marked effect

oneup [,wən-'əp, 'wən-] -vt

  1. to practice one-upmanship on

one up -adj

  1. being in a position of advantage usu. used with on

oneup·man·ship [,wən-'əp-mən-,ship] -n

  1. the art or practice of outdoing or keeping one jump ahead of a friend or competitor
    • engaged in a round of verbal oneupmanship

oneway -adj

  1. that moves in or allows movement in only one direction
    • a oneway street
  2. one-sided, unilateral
    • a oneway conversation
  3. that functions in only one of two or more ways

on·go·ing ['ȯn-,gō-iŋ, 'än-, -,gȯ(-)iŋ] -adj, n

  1. being actually in process
  2. continuing
  3. continuously moving forward : growing

on·ion ['ən-yən] -n, adj

  1. a widely cultivated Asian herb ( Allium cepa) of the lily family with pungent edible bulbs
  2. its bulb
  3. any of various plants of the same genus as the onion

onion dome -n, adj

  1. a dome (as of a church) having the general shape of an onion

onion ring -n

  1. a ring of sliced onion coated with batter or crumbs and fried

on·ion·skin [-,skin] -n

  1. a thin strong translucent paper of very light weight

oni·um ['ō-nē-əm] -adj

  1. being or characterized by a usu. complex cation

on·line ['ȯn-'līn, 'än-'līn] -adj, adv

  1. connected to, served by, or available through a system and esp. a computer or telecommunications system (as the Internet)
    • an online database
  2. done while connected to such a system
    • online shopping

on·look·er ['ȯn-,lu̇-kər, 'än-] -n, adj

  1. one that looks on
  2. a passive spectator

on·ly ['ōn-lē] -adj

  1. unquestionably the best : peerless
  2. alone in a class or category : sole
    • the only one left
    • the only known species
  3. having no brother or sister
    • an only child
  4. few
    • one of the only areas not yet explored

only -adv

  1. as a single fact or instance and nothing more or different : merely
    • has only lost one election -- George Orwell
  2. solely, exclusively
    • known only to him
  3. at the very least
    • it was only too true
  4. in the final outcome
    • will only make you sick
  5. with nevertheless the final result
    • won the battles, only to lose the war
  6. as recently as : not before
    • only last week
    • only in the last year did she get recognition
  7. in the immediate past
    • only just talked to her
  8. with the restriction that : but
    • you may go, only come back early
  9. and yet : however
    • they look very nice, only we can't use them
  10. were it not that : except
    • I'd introduce you to her, only you'd win her -- Jack London

ono ['ō-(,)nō] -n

  1. wahoo

on·o·mas·tic [,ä-nə-'mas-tik] -adj, adv

  1. of, relating to, or consisting of a name or names

on·o·mas·tics [-tiks] -n pl but sing or pl in constr, n

  1. the science or study of the origins and forms of words esp. as used in a specialized field
  2. the science or study of the origin and forms of proper names of persons or places
  3. the system underlying the formation and use of words esp. for proper names or of words used in a specialized field

on·o·ma·tol·o·gy [,ä-nə-mə-'tä-lə-jē] -n

  1. onomastics

on·o·mato·poe·ia [,ä-nə-,mä-tə-'pē-ə, -,ma-] -n, adj, adv

  1. the naming of a thing or action by a vocal imitation of the sound associated with it (as buzz, hiss)
  2. the use of words whose sound suggests the sense

On·on·da·ga [,ä-nə(n)-'dȯ-gə, -'dā-, -'dä-] -n

  1. a member of an American Indian people of New York and Canada
  2. the Iroquoian language of the Onondaga people

onramp ['ȯn-,ramp, 'än-] -n

  1. a ramp by which one enters a limited-access highway

on·rush [-,rəsh] -n, adj

  1. a rushing forward or onward
  2. onset

onscreen ['ȯn-'skrēn, 'än-] -adv or adj

  1. in a motion picture or a television program
  2. on a computer or television screen

on·set [-,set] -n

  1. attack, assault
    • withstand the onset of the army
  2. beginning, commencement
    • the onset of winter

on·shore ['ȯn-,shȯr, 'än-] -adj, adv

  1. coming or moving from the water toward or onto the shore
    • an onshore wind
  2. situated on or near the shore as distinguished from being in deep or open water
  3. situated on land
  4. domestic
    • onshore markets

on·side [-'sīd] -adv or adj

  1. not offside : in a position legally to play or receive the ball or puck

onside kick -n

  1. a kickoff in football in which the ball travels just far enough to be legally recoverable by the kicking team

onsite [-'sīt] -adv or adj

  1. at a particular place esp. of business
    • printed onsite
    • onsite day care

on·slaught ['än-,slȯt, 'ȯn-] -n

  1. an esp. fierce attack
  2. something resembling such an attack
    • an onslaught of technological changes

on·stage ['ȯn-'stāj, 'än-, -,stāj] -adv or adj

  1. on or onto a stage : on a part of the stage visible to the audience

on·stream ['ȯn-'strēm, 'än-] -adv or adj

  1. in or into production
    • plants scheduled to come onstream

ont- -comb form

  1. being : existence
    • onto logy
  2. organism
    • onto geny

ontar·get ['än-'tär-gət] -adj

  1. exactly appropriate : accurate
    • ontarget advice

onthejob -adj

  1. of, relating to, or being something (as training or experience) learned, gained, or done while working at a job

on·tic ['än-tik] -adj, adv

  1. of, relating to, or having real being

on·to ['ȯn-(,)tü, 'än-] -prep

  1. to a position on
  2. in or into a state of awareness about
    • put me onto your methods
  3. used as a function word to indicate a set each element of which is the image of at least one element of another set
    • a function mapping the set S onto the set T

onto -adj

  1. mapping elements in such a way that every element in one set is the image of at least one element in another set
    • a function that is one-to-one and onto

on·to·gen·e·sis [,än-tə-'je-nə-səs] -n

  1. ontogeny

on·to·ge·net·ic [-jə-'ne-tik] -adj, adv

  1. of, relating to, or appearing in the course of ontogeny
  2. based on visible morphological characters

on·tog·e·ny [än-'tä-jə-nē] -n

  1. the development or course of development esp. of an individual organism

on·to·log·i·cal [,än-tə-'lä-ji-kəl] -adj, adv

  1. of or relating to ontology
  2. relating to or based upon being or existence

ontological argument -n

  1. an argument for the existence of God based upon the meaning of the term God

on·tol·o·gy [än-'tä-lə-jē] -n

  1. a branch of metaphysics concerned with the nature and relations of being
  2. a particular theory about the nature of being or the kinds of things that have existence

onus ['ō-nəs] -n

  1. burden
  2. a disagreeable necessity : obligation
  3. blame
  4. stigma
  5. burden of proof

on·ward ['ȯn-wərd, 'än-] -adv

  1. toward or at a point lying ahead in space or time : forward

onward -adj

  1. directed or moving onward : forward

on·y·choph·o·ran [,ä-ni-'kä-fə-rən] -n, adj

  1. peripatus

on·yx ['ä-niks] -n

  1. a translucent chalcedony in parallel layers of different colors