os ['äs] -n

  1. bone
  2. orifice

Os -symbol

  1. osmium

OS -abbr

  1. left eye
  2. Old Style
  3. operating system
  4. out of stock

Osage [ō-'sāj, 'ō-,] -n

  1. a member of an American Indian people orig. of Missouri
  2. the Siouan language of the Osage people

Osage orange -n

  1. an ornamental usu. thorny U.S. tree ( Maclura pomifera) of the mulberry family with shiny ovate leaves and hard bright orange wood
  2. its yellowish-green globose fruit

Os·can ['äs-kən] -n

  1. a member of a people of ancient Italy occupying Campania
  2. the language of the Oscan people

Os·car ['äs-kər] -trademark

  1. used esp. for any of a number of golden statuettes awarded annually by a professional organization for notable achievement in motion pictures

Oscar

  1. a communications code word for the letter o

os·cil·late ['ä-sə-,lāt] -vi, adj

  1. to swing backward and forward like a pendulum
  2. to move or travel back and forth between two points
  3. to vary between opposing beliefs, feelings, or theories
  4. to vary above and below a mean value

os·cil·la·tion [,ä-sə-'lā-shən] -n, adj

  1. the action or state of oscillating
  2. variation, fluctuation
  3. a flow of electricity changing periodically from a maximum to a minimum
  4. a flow periodically changing direction
  5. a single swing (as of an oscillating body) from one extreme limit to the other

os·cil·la·tor ['ä-sə-,lā-tər] -n

  1. one that oscillates
  2. a device for producing alternating current
  3. a radio-frequency or audio-frequency generator

oscillo- -comb form

  1. wave : oscillation
    • oscillo scope

os·cil·lo·gram [ä-'si-lə-,gram, ə-] -n

  1. a record made by an oscillograph or oscilloscope

os·cil·lo·graph [-,graf] -n, adj, adv

  1. an instrument for recording alternating current wave forms or other electrical oscillations

os·cil·lo·scope [ä-'si-lə-,skōp, ə-] -n, adj

  1. an instrument in which the variations in a fluctuating electrical quantity appear temporarily as a visible wave form on the fluorescent screen of a cathode-ray tube

os·cine ['ä-,sīn] -adj, n

  1. of or relating to a large suborder (Oscines) of passerine birds (as larks, shrikes, finches, orioles, and crows) characterized by a vocal apparatus highly specialized for singing

Os·coUm·bri·an [,äs-kō-'əm-brē-ən] -n

  1. a subdivision of the Italic branch of the Indo-European language family containing Oscan and Umbrian

os·cu·late ['äs-kyə-,lāt] -vt

  1. kiss

os·cu·la·tion [,äs-kyə-'lā-shən] -n, adj

  1. the act of kissing
  2. kiss

os·cu·lum ['äs-kyə-ləm] -n

  1. an excurrent opening of a sponge

Osee ['ō-,zē, ō-'zā-ə] -n

  1. hosea

oset·ra [(,)ō-'se-trə] -n

  1. a golden or brownish caviar from a sturgeon (as Acipenser gueldenstaedtiiof the Caspian Sea) with roe somewhat smaller than the beluga and having a usu. nutty flavor
  2. the fish

OSHA -abbr

  1. Occupational Safety and Health Administration

osier ['ō-zhər] -n

  1. any of various willows (esp. Salix viminalis) whose pliable twigs are used for furniture and basketry
  2. a willow rod used in basketry
  3. any of several American dogwoods
  4. red osier

Osi·ris [ō-'sī-rəs] -n

  1. the Egyptian god of the underworld and husband and brother of Isis

Os·man·li [äz-'man-lē] -n

  1. ottoman
  2. turkish

os·me·te·ri·um [,äz-mə-'tir-ē-əm] -n

  1. a protrusible glandular process of swallowtail larvae that emits a disagreeable odor for defensive purposes

osmic acid -n

  1. osmium tetroxide

os·mi·um ['äz-mē-əm] -n

  1. a blue-gray or blue-black hard brittle very heavy polyvalent metallic element with a high melting point that is used esp. as a catalyst and in hard alloys

osmium tetroxide -n

  1. a crystalline compound OsO 4that is an oxide of osmium, has a poisonous irritating vapor, and is used as a catalyst, oxidizing agent, and biological fixative and stain

os·mol ['äz-,mōl, 'äs-] -n

  1. a standard unit of osmotic pressure based on a one molal concentration of an ion in a solution

os·mo·lal·i·ty [,äz-mō-'la-rə-tē, ,äs-] -n, adj

  1. the concentration of an osmotic solution esp. when measured in osmols or milliosmols per 1000 grams of solvent

os·mo·lar·i·ty [,äz-mō-'la-rə-tē, ,äs-] -n, adj

  1. the concentration of an osmotic solution esp. when measured in osmols or milliosmols per liter of solution

os·mom·e·ter [äz-'mä-mə-tər, äs-] -n, adj

  1. an apparatus for measuring osmotic pressure

os·mo·reg·u·la·tion ['äz-mō-,re-gyə-'lā-shən, 'äs-] -n, adj

  1. regulation of osmotic pressure esp. in the body of a living organism

os·mo·sis [äz-'mō-səs, äs-] -n

  1. movement of a solvent (as water) through a semipermeable membrane (as of a living cell) into a solution of higher solute concentration that tends to equalize the concentrations of solute on the two sides of the membrane
  2. a process of absorption or diffusion suggestive of the flow of osmotic action
  3. a usu. effortless often unconscious assimilation
    • learned a number of languages by osmosis -- Roger Kimball

os·mot·ic [-'mä-tik] -adj, adv

  1. of, relating to, caused by, or having the properties of osmosis

osmotic pressure -n

  1. : the pressure produced by or associated with osmosis and dependent on molar concentration and absolute temperature: as
  2. the maximum pressure that develops in a solution separated from a solvent by a membrane permeable only to the solvent
  3. the pressure that must be applied to a solution to just prevent osmosis

osmotic shock -n

  1. a rapid change in the osmotic pressure (as by transfer to a medium of different concentration) affecting a living system

os·mun·da [äz-'mən-də] -n

  1. any of a genus ( Osmunda) of rather large ferns (as the cinnamon fern) with pinnate or bipinnate fronds and fibrous creeping rhizomes

os·prey ['äs-prē, -,prā] -n

  1. a large fish-eating hawk ( Pandion haliaetus) with long wings that is dark brown above and mostly pure white below
  2. a feather trimming used for millinery

OSS -abbr

  1. Office of Strategic Services

ossa ['äs] -n

(variant of os)

  1. bone
  2. orifice

os·se·in ['ä-sē-ən] -n

  1. the collagen of bones

os·se·ous ['ä-sē-əs] -adj

  1. bony

Os·sete ['ä-,sēt] -n, adj or n

  1. a member of a people of the central Caucasus

Os·set·ic [ä-'se-tik] -n

  1. the Iranian language of the Ossetes

Os·si·an·ic [,ä-sē-'a-nik, -shē-] -adj

  1. of, relating to, or resembling the legendary Irish bard Ossian, the poems ascribed to him, or the rhythmic prose style used by James Macpherson in the poems he claimed to have translated from Ossian

os·si·cle ['ä-si-kəl] -n, adj

  1. a small bone or bony structure (as the malleus, incus, or stapes)

os·si·fi·ca·tion [,ä-sə-fə-'kā-shən] -n

  1. the natural process of bone formation
  2. the hardening (as of muscular tissue) into a bony substance
  3. a mass or particle of ossified tissue
  4. a tendency toward or state of being molded into a rigid, conventional, sterile, or unimaginative condition

os·si·frage ['ä-sə-frij, -,frāj] -n

  1. lammergeier

os·si·fy ['ä-sə-,fī] -vb

  1. to change into bone
  2. to become hardened or conventional and opposed to change
  3. to change (as cartilage) into bone
  4. to make rigidly conventional and opposed to change

os·so bu·co [,ō-sō-'bü-(,)kō, ,ȯ-sō-] -n

  1. a dish of veal shanks braised with vegetables, white wine, and seasoned stock

os·su·ary ['ä-shə-,wer-ē, -syə-, -sə-] -n

  1. a depository for the bones of the dead

oste- -comb form

  1. bone
    • oste al
    • osteo myelitis

os·te·al ['äs-tē-əl] -adj

  1. of, relating to, or resembling bone
  2. affecting or involving bone or the skeleton

os·te·i·tis [,äs-tē-'ī-təs] -n

  1. inflammation of bone

os·ten·si·ble [ä-'sten(t)-sə-bəl, ə-] -adj

  1. intended for display : open to view
  2. being such in appearance : plausible rather than demonstrably true or real
    • the ostensible purpose for the trip

os·ten·si·bly [-blē] -adv

  1. in an ostensible manner
  2. to all outward appearances

os·ten·sive [ä-'sten(t)-siv] -adj, adv

  1. ostensible
  2. of, relating to, or constituting definition by exemplifying the thing or quality being defined

os·ten·so·ri·um [,äs-tən-'sȯr-ē-əm, -,ten-] -n

  1. monstrance

os·ten·ta·tion [,äs-tən-'tā-shən] -n

  1. excessive display : pretentiousness
  2. an act of displaying

os·ten·ta·tious [-shəs] -adj, adv, n

  1. marked by or fond of conspicuous or vainglorious and sometimes pretentious display

os·te·o·ar·thri·tis [,äs-tē-ō-är-'thrī-təs] -n, adj

  1. arthritis marked by degeneration of the cartilage and bone of joints

os·te·o·blast ['äs-tē-ə-,blast] -n, adj

  1. a bone-forming cell

os·te·o·clast ['äs-tē-ə-,klast] -n, adj

  1. any of the large multinucleate cells closely associated with areas of bone resorption

os·te·o·cyte ['äs-tē-ə-,sīt] -n

  1. a cell that is characteristic of adult bone and is isolated in a lacuna of the bone substance

os·te·o·gen·e·sis [,äs-tē-ə-'je-nə-səs] -n

  1. development and formation of bone

osteogenesis im·per·fec·ta [-,im-(,)pər-'fek-tə] -n

  1. a hereditary disease marked esp. by extreme brittleness of bones and caused by defective or insufficient collagen

os·te·o·gen·ic [,äs-tē-ə-'je-nik] -adj

  1. producing bone
  2. originating in bone

osteogenic sarcoma -n

  1. osteosarcoma

os·te·oid ['äs-tē-,ȯid] -adj

  1. resembling bone

osteoid -n

  1. uncalcified bone matrix

os·te·ol·o·gy [,äs-tē-'ä-lə-jē] -n, adj

  1. a branch of anatomy dealing with the bones
  2. the bony structure of an organism

os·te·o·ma [,äs-tē-'ō-mə] -n

  1. a benign tumor composed of bone tissue

os·te·o·ma·la·cia [,äs-tē-ō-mə-'lā-sh(ē-)ə] -n

  1. a disease of adults that is characterized by softening of the bones and is analogous to rickets in the young

os·te·o·my·e·li·tis [-,mī-ə-'lī-təs] -n

  1. an infectious usu. painful inflammatory disease of bone often of bacterial origin that may result in the death of bone tissue

os·te·o·path ['äs-tē-ə-,path] -n

  1. a practitioner of osteopathy

os·te·op·a·thy [,äs-tē-'ä-pə-thē] -n, adj, adv

  1. a system of medical practice based on a theory that diseases are due chiefly to loss of structural integrity which can be restored by manipulation of the parts supplemented by therapeutic measures (as use of drugs or surgery)

os·teo·phyte ['äs-tē-ə-,fīt] -n

  1. a pathological bony outgrowth

os·te·o·plas·ty ['äs-tē-ə-,plas-tē] -n, adj

  1. plastic surgery on bone
  2. replacement of lost bone tissue or reconstruction of defective bony parts

os·te·o·po·ro·sis [,äs-tē-ō-pə-'rō-səs] -n, adj

  1. a condition that affects esp. older women and is characterized by decrease in bone mass with decreased density and enlargement of bone spaces producing porosity and fragility

os·te·o·sar·co·ma [-sär-'kō-mə] -n

  1. a sarcoma derived from bone or containing bone tissue

osti·na·to [,äs-tə-'nä-(,)tō, ,ȯs-] -n

  1. a musical figure repeated persistently at the same pitch throughout a composition

os·ti·ole ['äs-tē-,ōl] -n

  1. a small bodily aperture, orifice, or pore

os·ti·um ['äs-tē-əm] -n

  1. a mouthlike opening in a bodily part (as a fallopian tube or a blood vessel)

ostler ['häs-lər, 'äs-] -n

(variant of hostler)

  1. one who takes care of horses or mules
  2. one who moves locomotives in and out of a roundhouse
  3. one who services locomotives

os·to·my ['äs-tə-mē] -n

  1. an operation (as a colostomy) to create an artificial passage for bodily elimination

os·tra·cise [-,sīz] -vt

(variant of ostracize)

  1. to exile by ostracism
  2. to exclude from a group by common consent

os·tra·cism ['äs-trə-,si-zəm] -n

  1. a method of temporary banishment by popular vote without trial or special accusation practiced in ancient Greece
  2. exclusion by general consent from common privileges or social acceptance

os·tra·cize [-,sīz] -vt

  1. to exile by ostracism
  2. to exclude from a group by common consent

os·tra·cod ['äs-trə-,käd] -n

  1. any of a subclass (Ostracoda) of very small aquatic crustaceans that have the body enclosed in a bivalve carapace, the body segmentation obscured, the abdomen rudimentary, and only seven pairs of appendages

os·tra·co·derm ['äs-trə-kō-,dərm, äs-'tra-kə-] -n

  1. any of the early fossil jawless fishes of the Lower Paleozoic usu. having a bony covering of plates or scales

os·tra·con ['äs-trə-,kän] -n

  1. a fragment (as of pottery) containing an inscription usu. used in pl.

os·trich ['äs-trich, 'ȯs- also -trij] -n, adj

  1. a swift-footed 2-toed flightless ratite bird ( Struthio camelus) of Africa that is the largest of existing birds and often weighs 300 pounds (140 kilograms)
  2. rhea
  3. leather made from ostrich skin
  4. one who attempts to avoid danger or difficulty by refusing to face it

ostrich fern -n

  1. any of a genus ( Matteuccia) of temperate-zone ferns
  2. a tall fern ( M. struthiopteris) with graceful arched fronds which are the source of edible fiddleheads

Os·tro·goth ['äs-trə-,gäth] -n, adj

  1. a member of the eastern division of the Goths

Os·we·go tea [ä-'swē-gō-] -n

  1. a No. American mint ( Monarda didyma) with showy scarlet irregular flowers