OC -abbr

  1. off center
  2. officer candidate
  3. on center
  4. on course
  5. over-the-counter

oca ['ō-kə] -n

  1. either of two So. American wood sorrels ( Oxalis crenataand O. tuberosa) cultivated for their edible tubers
  2. the tuber of an oca

oc·a·ri·na [,ä-kə-'rē-nə] -n

  1. a simple wind instrument typically having an oval body with finger holes and a projecting mouthpiece

Oc·cam's razor ['ä-kəmz-] -n

  1. a scientific and philosophic rule that entities should not be multiplied unnecessarily which is interpreted as requiring that the simplest of competing theories be preferred to the more complex or that explanations of unknown phenomena be sought first in terms of known quantities

oc·ca·sion [ə-'kā-zhən] -n

  1. a favorable opportunity or circumstance
    • did not have occasion to talk with them
  2. a state of affairs that provides a ground or reason
    • the occasion of the discord was their mutual intolerance
  3. an occurrence or condition that brings something about
  4. the immediate inciting circumstance as distinguished from the fundamental cause
    • his insulting remark was the occasion of a bitter quarrel
  5. happening, incident
  6. a time at which something happens : instance
  7. a need arising from a particular circumstance
  8. a personal want or need usu. used in pl.
  9. affairs, business
  10. a special event or ceremony : celebration

occasion [-'kāzh-niŋ, -'kā-zhə-] -vt

  1. bring about, cause

oc·ca·sion·al [-'kāzh-nəl, -'kā-zhə-nᵊl] -adj

  1. of or relating to a particular occasion
    • a budget able to meet occasional demands as well as regular ones
  2. created for a particular occasion
    • occasional verse
  3. acting as the occasion or contributing cause of something
  4. encountered, occurring, appearing, or taken at irregular or infrequent intervals
    • occasional visitors
    • an occasional vacation
  5. acting in a specified capacity from time to time
    • an occasional lecturer
  6. designed or constructed to be used as the occasion demands
    • occasional furniture

oc·ca·sion·al·ly [-'kāzh-nə-lē, -'kā-zhə-nᵊl-ē] -adv

  1. on occasion : now and then
    • dines out occasionally

Oc·ci·dent ['äk-sə-dənt, -,dent] -n

  1. west

oc·ci·den·tal [,äk-sə-'den-tᵊl] -adj, adv

  1. of, relating to, or situated in the Occident : western
  2. of or relating to Occidentals

Occidental -n

  1. a member of one of the occidental peoples
  2. a person of European ancestry

Oc·ci·den·tal·ism [,äk-sə-'den-tə-,li-zəm] -n

  1. the characteristic features of occidental peoples or culture

oc·ci·den·tal·ize [-tə-,līz] -vt

  1. to make occidental (as in culture)

oc·cip·i·tal [äk-'si-pə-tᵊl] -adj, n, adv

  1. of, relating to, or located within or near the occiput or the occipital bone

occipital bone -n

  1. a compound bone that forms the posterior part of the skull and bears a condyle by which the skull articulates with the atlas

occipital condyle -n

  1. an articular surface on the occipital bone by which the skull articulates with the atlas

occipital lobe -n

  1. the posterior lobe of each cerebral hemisphere that bears the visual cortex and has the form of a 3-sided pyramid

oc·ci·put ['äk-sə-(,)pət] -n

  1. the back part of the head or skull

Oc·ci·tan ['äk-sə-,tan] -n, adj

  1. a Romance language spoken in southern France

oc·clude [ə-'klüd, ä-] -vb

  1. to close up or block off : obstruct
    • a thrombus occluding a coronary artery
  2. conceal
  3. sorb
  4. to come into contact with cusps of the opposing teeth fitting together
    • his teeth do not occlude properly
  5. to become occluded

occluded front -n

  1. occlusion

oc·clu·sal [ə-'klü-səl, ä-, -zəl] -adj

  1. of or relating to the grinding or biting surface of a tooth or to occlusion of the teeth

oc·clu·sion [ə-'klü-zhən] -n

  1. : the act of occluding : the state of being occluded: as
  2. the complete obstruction of the breath passage in the articulation of a speech sound
  3. the bringing of the opposing surfaces of the teeth of the two jaws into contact
  4. the relation between the surfaces when in contact
  5. the inclusion or sorption of gas trapped during solidification of a material
  6. the front formed by a cold front overtaking a warm front and lifting the warm air above the earth's surface

oc·clu·sive [-siv, -ziv] -adj

  1. serving to occlude
  2. characterized by occlusion

oc·cult [ə-'kəlt, ä-] -vt, n

  1. to shut off from view or exposure : cover, eclipse
  2. not revealed : secret
  3. not easily apprehended or understood : abstruse, mysterious
  4. hidden from view : concealed
  5. of or relating to the occult
  6. not manifest or detectable by clinical methods alone
    • occult carcinoma
  7. not present in macroscopic amounts
    • occult blood in a stool

occult [same as ²] -n

  1. matters regarded as involving the action or influence of supernatural or supernormal powers or some secret knowledge of them used with the

oc·cul·ta·tion [,ä-(,)kəl-'tā-shən] -n

  1. the state of being hidden from view or lost to notice
  2. the interruption of the light from a celestial body or of the signals from a spacecraft by the intervention of a celestial body
  3. an eclipse of a star or planet by the moon

oc·cult·ism [ə-'kəl-,ti-zəm, ä-; 'ä-,kəl-] -n

  1. occult theory or practice : belief in or study of the action or influence of supernatural or supernormal powers

oc·cu·pan·cy ['ä-kyə-pən(t)-sē] -n

  1. the fact or condition of holding, possessing, or residing in or on something
    • occupancy of the estate
  2. the act or fact of taking or having possession (as of unowned land) to acquire ownership
  3. the fact or condition of being occupied
    • occupancy by more than 400 persons is unlawful
  4. the use to which a property is put
    • industrial occupancy
  5. a building or part of a building intended to be occupied (as by a tenant)

oc·cu·pant [-pənt] -n

  1. one who acquires title by occupancy
  2. one who occupies a particular place
  3. resident

oc·cu·pa·tion [,ä-kyə-'pā-shən] -n, adj, adv

  1. an activity in which one engages
    • pursuing pleasure has been his major occupation
  2. the principal business of one's life : vocation
  3. the possession, use, or settlement of land : occupancy
  4. the holding of an office or position
  5. the act or process of taking possession of a place or area : seizure
  6. the holding and control of an area by a foreign military force
  7. the military force occupying a country or the policies carried out by it

occupational therapy -n

  1. therapy based on engagement in meaningful activities of daily life (as self-care skills, education, work, or social interaction) esp. to enable or encourage participation in such activities despite impairments or limitations in physical or mental functioning

oc·cu·py ['ä-kyə-,pī] -vt, n

  1. to engage the attention or energies of
  2. to take up (a place or extent in space)
    • this chair is occupied
    • the fireplace will occupy this corner of the room
  3. to take or fill (an extent in time)
    • the hobby occupies all of my free time
  4. to take or hold possession or control of
    • enemy troops occupied the ridge
  5. to fill or perform the functions of (an office or position)
  6. to reside in as an owner or tenant

oc·cur [ə-'kər] -vi

  1. to be found or met with : appear
  2. to come into existence : happen
  3. to come to mind
    • an idea that has occurred to me

oc·cur·rence [ə-'kər-ən(t)s, -'kə-rən(t)s] -n

  1. something that occurs
    • a startling occurrence
  2. the action or instance of occurring
    • the repeated occurrence of petty theft in the locker room

oc·cur·rent [ə-'kər-ənt, -'kə-rənt] -adj

  1. occurring at a particular time or place : current
  2. incidental

occurrent -n

  1. something that occurs as distinguished from something that continues to exist

OCD -abbr

  1. obsessive-compulsive disorder

ocean ['ō-shən] -n

  1. the whole body of salt water that covers nearly three fourths of the surface of the earth
  2. any of the large bodies of water (as the Atlantic Ocean) into which the great ocean is divided
  3. a very large or unlimited space or quantity

ocean·ar·i·um [,ō-shə-'ner-ē-əm] -n

  1. a large marine aquarium

ocean·front ['ō-shən-,frənt] -n

  1. a shore area on the ocean

ocean·go·ing [-,gō-iŋ] -adj

  1. of, relating to, or designed for travel on the ocean

oce·an·ic [,ō-shē-'a-nik] -adj

  1. of or relating to the ocean
  2. occurring in or frequenting the ocean and esp. the open sea as distinguished from littoral or neritic waters
  3. vast, great

Oce·anid [ō-'sē-ə-nəd] -n

  1. any of the ocean nymphs that are daughters of Oceanus and Tethys in Greek mythology

ocean·og·ra·phy [,ō-shə-'nä-grə-fē] -n, adj, adv

  1. a science that deals with the oceans and includes the delimitation of their extent and depth, the physics and chemistry of their waters, marine biology, and the exploitation of their resources

ocean·ol·o·gy [,ō-shə-'nä-lə-jē] -n

  1. oceanography
  2. the science of marine resources and technology

ocean perch -n

  1. : any of several marine scorpaenid food fishes (genus Sebastes):
  2. redfish
  3. a related food fish ( S. fasciatus)
  4. one ( S. alutus) abundant in the northeastern Pacific from Japan to the Bering Sea to southern California

ocean sunfish -n

  1. a large bony fish ( Mola molaof the family Molidae, order Tetraodontiformes) having high dorsal and anal fins and a body nearly oval in outline and attaining a length of 10 feet (3 meters) and a weight in excess of 2 tons (1.8 metric tons)

Oce·anus [ō-'sē-ə-nəs] -n

  1. a Titan who rules over a great river encircling the earth in Greek mythology

ocel·lus [ō-'se-ləs] -n, adj

  1. a minute simple eye or eyespot of an invertebrate
  2. an eyelike colored spot (as on a peacock feather or the wings of some butterflies)

oce·lot ['ä-sə-,lät, 'ō-] -n

  1. a medium-sized American wildcat ( Felis pardalis) that ranges from Texas to northern Argentina and has a tawny-yellow or grayish coat dotted and striped with black

ocher ['ō-kər] -n, adj

  1. an earthy usu. red or yellow and often impure iron ore used as a pigment
  2. the color of ocher
  3. the color of yellow ocher

och·loc·ra·cy [ä-'klä-krə-sē] -n, adj

  1. government by the mob : mob rule

oci·cat ['ä-sē-,kat] -n

  1. any of a breed of domestic cats developed by crossing Siamese, American shorthair, and Abyssinian cats and having a short spotted coat

oco·ti·llo [,ō-kə-'tē-(,)yō] -n

  1. a thorny scarlet-flowered candlewood ( Fouquieria splendensof the family Fouquieriaceae) of the southwestern U.S. and Mexico

OCR -abbr

  1. optical character reader; optical character recognition

OCS -abbr

  1. officer candidate school
  2. Old Church Slavic; Old Church Slavonic

Oct -abbr

  1. October

octa- -comb form

  1. eight
    • oct ane
    • octo roon

oc·ta·gon ['äk-tə-,gän] -n, adj, adv

  1. a polygon of eight angles and eight sides

oc·ta·he·dral [,äk-tə-'hē-drəl] -adj, adv

  1. having eight plane faces
  2. of, relating to, or formed in octahedrons

oc·ta·he·dron [-drən] -n

  1. a solid bounded by eight plane faces

oc·tal ['äk-tᵊl] -adj

  1. of, relating to, or being a number system with a base of eight

oc·tam·e·ter [äk-'ta-mə-tər] -n

  1. a line of verse consisting of eight metrical feet

oc·tane ['äk-,tān] -n

  1. any of several isomeric liquid alkanes C 8H 18
  2. octane number

octane number -n

  1. a number that is used to measure the antiknock properties of a liquid motor fuel (as gasoline) with a higher number indicating a smaller likelihood of knocking called also octane rating

oc·tant ['äk-tənt] -n

  1. an instrument for observing altitudes of a celestial body from a moving ship or aircraft
  2. any of the eight parts into which a space is divided by three coordinate planes

oc·ta·pep·tide [,äk-tə-'pep-,tīd] -n

  1. a protein fragment or molecule (as oxytocin or vasopressin) that consists of eight amino acids linked in a polypeptide chain

oc·tave ['äk-tiv, -təv, -,tāv] -n

  1. an 8-day period of observances beginning with a festival day
  2. a stanza of eight lines : ottava rima
  3. the first eight lines of an Italian sonnet
  4. a musical interval embracing eight diatonic degrees
  5. a tone or note at this interval
  6. the harmonic combination of two tones an octave apart
  7. the whole series of notes, tones, or digitals comprised within this interval and forming the unit of the modern scale
  8. an organ stop giving tones an octave above those corresponding to the keys
  9. the interval between two frequencies (as in an electromagnetic spectrum) having a ratio of 2 to 1
  10. a group of eight

oc·ta·vo [äk-'tā-(,)vō, -'tä-] -n

  1. the size of a piece of paper cut eight from a sheet
  2. a book, a page, or paper of this size

oc·tet [äk-'tet] -n

  1. a musical composition for eight instruments or voices
  2. : a group or set of eight: as
  3. octave
  4. the performers of an octet

Oc·to·ber [äk-'tō-bər] -n

  1. the 10th month of the Gregorian calendar

oc·to·ge·nar·i·an [,äk-tə-jə-'ner-ē-ən] -n, adj

  1. a person whose age is in the eighties

oc·to·ploid ['äk-tə-,plȯid] -adj, n

  1. having a chromosome number eight times the basic haploid chromosome number

oc·to·pod ['äk-tə-,päd] -n, adj

  1. any of an order (Octopoda) of cephalopod mollusks (as an octopus or argonaut) that have eight arms bearing sessile suckers

oc·to·pus ['äk-tə-pəs, -,pu̇s] -n

  1. any of a genus ( Octopus) of cephalopod mollusks that have eight muscular arms equipped with two rows of suckers
  2. any octopod excepting the paper nautilus
  3. something that resembles an octopus esp. in having many centrally directed branches

oc·to·roon [,äk-tə-'rün] -n

  1. a person of one-eighth black ancestry

oc·to·syl·lab·ic [,äk-tə-sə-'la-bik] -adj, n

  1. consisting of eight syllables
  2. composed of verses of eight syllables

oc·to·syl·la·ble ['äk-tə-,si-lə-bəl, ,äk-tə-'] -n

  1. a word or line of eight syllables

oc·to·thorpe ['äk-tə-,thȯrp, -tō-] -n

  1. the symbol #

oc·u·lar ['ä-kyə-lər] -adj

  1. done or perceived by the eye
    • ocular inspection
  2. based on what has been seen
    • ocular testimony
  3. of or relating to the eye
    • ocular muscles
  4. resembling an eye in form or function

ocular -n

  1. eyepiece

oc·u·lar·ist ['ä-kyə-lə-rist] -n

  1. a person who makes and fits artificial eyes

oc·u·list ['ä-kyə-list] -n

  1. ophthalmologist
  2. optometrist

oc·u·lo·mo·tor [,ä-kyə-lə-'mō-tər] -adj

  1. moving or tending to move the eyeball
  2. of or relating to the oculomotor nerve

oculomotor nerve -n

  1. either of the pair of chiefly motor nerves that comprise the third pair of cranial nerves, arise from the midbrain, and supply four muscles of the eye

oc·u·lus ['ä-kyə-ləs] -n

  1. a circular or oval window
  2. a circular opening at the top of a dome