cortisone (n.) Look up cortisone at Dictionary.com
1949, coined by its discoverer, Dr. Edward C. Kendall, shortening of chemical name, 17-hydroxy-11 dehydrocorticosterone, ultimately from Latin corticis (genitive of cortex; see cortex). So called because it was obtained from the "cortex" of adrenal glands; originally called Compound E (1936).
corundum (n.) Look up corundum at Dictionary.com
"very hard mineral," 1728, from Anglo-Indian, from Tamil kurundam "ruby sapphire" (Sanskrit kuruvinda), which is of unknown origin.
coruscate (v.) Look up coruscate at Dictionary.com
1705, from Latin coruscatus, past participle of coruscare "to vibrate, glitter," perhaps from PIE *(s)ker- (2) "leap, jump about" (compare scherzo), but de Vaan considers this "a long shot." Related: Coruscated; coruscating.
coruscation (n.) Look up coruscation at Dictionary.com
late 15c., from Latin coruscationem (nominative coruscatio), noun of action from past participle stem of coruscare "to vibrate, glitter" (see coruscate).
corvee (n.) Look up corvee at Dictionary.com
mid-14c., "day's unpaid labor due to a lord by vassals under French feudal system" (abolished 1776), from Old French corvee (12c.), from Late Latin corrogata (opera) "requested work," from fem. past participle of Latin corrogare, from assimilated form of com "with" (see com-) + rogare "to ask," apparently a figurative use of a PIE verb meaning literally "to stretch out (the hand)," from PIE *rog-, variant of the root *reg- "move in a straight line."
corvette (n.) Look up corvette at Dictionary.com
1630s, also corvet, from French corvette "small, fast frigate" (15c.), perhaps from Middle Dutch korver "pursuit ship," or Middle Low German korf meaning both a kind of boat and a basket, or from Latin corbita (navis) "slow-sailing ship of burden, grain ship" from corbis "basket" (Gamillscheg is against this). The U.S. sports car was so named September 1952, after the warship, on a suggestion by Myron Scott, employee of Campbell-Ewald, Chevrolet's advertising agency. Italian corvetta, Spanish corbeta are French loan-words.
Corydon Look up Corydon at Dictionary.com
traditional poetic name for a shepherd or rustic swain, from Latin Corydon, from Greek Korydon, name of a shepherd in Theocritus and Virgil.
coryza (n.) Look up coryza at Dictionary.com
1630s, from medical Latin, from Greek koryza "running at the nose."
cosa nostra Look up cosa nostra at Dictionary.com
1963, "the Mafia in America," from Italian, literally "this thing of ours."
cosecant (n.) Look up cosecant at Dictionary.com
1706, from co, short for complement, + secant.
cosh (n.) Look up cosh at Dictionary.com
"stout stick," 1869, of unknown origin.
cosher (n.) Look up cosher at Dictionary.com
1630s, phonetic spelling of Irish coisir "feast, entertainment."
cosign (v.) Look up cosign at Dictionary.com
also co-sign, by 1944, from co- + sign (v.). Related: Cosigned; cosigning.
cosigner (n.) Look up cosigner at Dictionary.com
also co-signer, 1946, agent noun from cosign; earlier in this sense was cosignatory (1865).
cosine (n.) Look up cosine at Dictionary.com
1630s, contraction of co. sinus, abbreviation of Medieval Latin complementi sinus (see complement + sine).
cosmetic (n.) Look up cosmetic at Dictionary.com
c. 1600, "art of beautifying," from Latinized form of Greek kosmetike (tekhne) "the art of dress and ornament," from fem. of kosmetikos (see cosmetic (adj.)). Meaning "a preparation for beautifying" attested from 1640s (now often cosmetics).
cosmetic (adj.) Look up cosmetic at Dictionary.com
1640s, from French cosmétique (16c.), from Greek kosmetikos "skilled in adornment or arrangement," from kosmein "to arrange, adorn," from kosmos "order" (see cosmos). Figurative sense of "superficial" is from 1955. Related: Cosmetically.
cosmetologist (n.) Look up cosmetologist at Dictionary.com
1926, American English, from cosmetology + -ist. Won out over cosmetician.
cosmetology (n.) Look up cosmetology at Dictionary.com
1855, from French cosmétologie, from Latinized form of Greek kosmetos (see cosmetic) + -ology.
cosmic (adj.) Look up cosmic at Dictionary.com
1640s, from cosmo- + -ic. Originally "of this world" (which was the sense of Greek kosmikos); meaning "of the universe" is from 1846. Cosmical is attested from 1580s.
cosmo- Look up cosmo- at Dictionary.com
before a vowel cosm-, word-forming element from Latinized form of Greek kosmos (see cosmos). In older use, "the world, the universe;" since 1950s, especially of outer space.
cosmogony (n.) Look up cosmogony at Dictionary.com
1690s as "a theory of the creation;" 1766 as "the creation of the universe," from Latinized form of Greek kosmogonia "creation of the world," from kosmos "world, universe" (see cosmos) + -gonia "a begetting," from gonos "birth" (from PIE root *gene- "give birth, beget").
cosmography (n.) Look up cosmography at Dictionary.com
"description of the universe," mid-15c., from cosmo- + -graphy. Related: Cosmographic.
cosmological (adj.) Look up cosmological at Dictionary.com
1825, from cosmology + -ical.
cosmology (n.) Look up cosmology at Dictionary.com
1650s, from Modern Latin cosmologia, from Greek kosmos (see cosmos) + -logia "discourse" (see -logy). Related: Cosmological; cosmologist.
They cannot scare me with their empty spaces
Between stars--on stars where no human race is.
I have it in me so much nearer home
To scare myself with my own desert places.

[Robert Frost, from "Desert Places," 1936]
cosmonaut (n.) Look up cosmonaut at Dictionary.com
1959, Englishing of Russian kosmonavt, ultimately from Greek kosmos (see cosmos) + nautes "sailor" (from PIE root *nau- "boat").
cosmopolitan (adj.) Look up cosmopolitan at Dictionary.com
1844, from cosmopolite "citizen of the world" (q.v.) on model of metropolitan. The U.S. women's magazine of the same name was first published in 1886. Cosmopolitanism first recorded 1828.
cosmopolite (n.) Look up cosmopolite at Dictionary.com
late 16c., "man of the world; citizen of the world," from Greek kosmopolites "citizen of the world," from kosmos "world" (see cosmos) + polites "citizen" (see politic). In common use 17c. in a neutral sense; it faded out in 18c. but was revived from c. 1800 with a tinge of reproachfulness (opposed to patriot).
cosmos (n.) Look up cosmos at Dictionary.com
c. 1200 (but not popular until 1848, as a translation of Humboldt's Kosmos), from Latinized form of Greek kosmos "order, good order, orderly arrangement," a word with several main senses rooted in those notions: The verb kosmein meant generally "to dispose, prepare," but especially "to order and arrange (troops for battle), to set (an army) in array;" also "to establish (a government or regime);" "to deck, adorn, equip, dress" (especially of women). Thus kosmos had an important secondary sense of "ornaments of a woman's dress, decoration" (compare kosmokomes "dressing the hair") as well as "the universe, the world."

Pythagoras is said to have been the first to apply this word to "the universe," perhaps originally meaning "the starry firmament," but later it was extended to the whole physical world, including the earth. For specific reference to "the world of people," the classical phrase was he oikoumene (ge) "the inhabited (earth)." Septuagint uses both kosmos and oikoumene. Kosmos also was used in Christian religious writing with a sense of "worldly life, this world (as opposed to the afterlife)," but the more frequent word for this was aion, literally "lifetime, age."
Cossack (n.) Look up Cossack at Dictionary.com
1590s, from Russian kozak, from Turkish kazak "adventurer, guerilla, nomad," from qaz "to wander." The same Turkic root is the source of the people-name Kazakh and the nation of Kazakhstan.
cosset (v.) Look up cosset at Dictionary.com
1650s, "to fondle, caress, indulge," from a noun (1570s) meaning "lamb brought up as a pet" (applied to persons from 1590s), perhaps from Old English cot-sæta "one who dwells in a cot" (see cote (n.) + sit (v.)). Related: Coseted; coseting. Compare German Hauslamm, Italian casiccio.
cost (v.) Look up cost at Dictionary.com
late 14c., from Old French coster (Modern French coûter) "to cost," from cost (see cost (n.)).
cost (n.) Look up cost at Dictionary.com
c. 1200, from Old French cost (12c., Modern French coût) "cost, outlay, expenditure; hardship, trouble," from Vulgar Latin *costare, from Latin constare, literally "to stand at" (or with), with a wide range of figurative senses including "to cost." The idiom is the same one used in Modern English when someone says something "stands at X dollars" to mean it sells for X dollars. The Latin word is from com- "with" (see com-) + stare "to stand," from PIE root *sta- "to stand, make or be firm."
cost-effective (adj.) Look up cost-effective at Dictionary.com
also cost effective, 1967, from cost (n.) + effective.
costa (n.) Look up costa at Dictionary.com
Spanish costa "coast," from same Latin source as English coast (n.). Used in Britain from 1960s in jocular formations (costa geriatrica, costa del crime, etc.) in imitation of the names of Spanish tourist destinations.
costal (adj.) Look up costal at Dictionary.com
"pertaining to the ribs," 1630s, from French costal (16c.), from Medieval Latin costalis, from costa "a rib" (see coast (n.)).
costard (n.) Look up costard at Dictionary.com
late 13c., coster, perhaps from Anglo-French or Old French coste "rib" (from Latin costa "a rib;" see coast (n.)). A kind of large apple with prominent "ribs," i.e. one having a shape more like a green pepper than a plain, round apple. Also applied derisively to "the head." Common 14c.-17c. but limited to fruit-growers afterward.
costermonger (n.) Look up costermonger at Dictionary.com
1510s, "itinerant apple-seller" from coster (see costard) + monger (n.). Sense extended from "apple-seller" to any salesman who plied his wares from a street-cart. Contemptuous use is from Shakespeare ("2 Henry IV"), but reason is unclear.
costive (adj.) Look up costive at Dictionary.com
c. 1400, from Middle French costivé, from Latin constipatus, past participle of constipare (see constipation).
costly (adj.) Look up costly at Dictionary.com
late 14c., from cost + -ly (1). Earlier formation with the same sense were costful (mid-13c.), costious (mid-14c.).
costume (v.) Look up costume at Dictionary.com
1823, from costume (n.). Related: Costumed; costuming.
costume (n.) Look up costume at Dictionary.com
1715, "style of dress," an art term, from French costume (17c.), from Italian costume "fashion, habit," from Latin consuetudinem (nominative consuetudo) "custom, habit, usage." Essentially the same word as custom but arriving by a different etymology. From "customary clothes of the particular period in which the scene is laid," meaning broadened by 1818 to "any defined mode of dress." Costume jewelry is first attested 1933.
cosy (adj.) Look up cosy at Dictionary.com
chiefly British form of cozy.
cot (n.1) Look up cot at Dictionary.com
"small bed," 1630s, from Hindi khat "couch, hammock," from Sanskrit khatva, probably from a Dravidian source (compare Tamil kattil "bedstead").
cot (n.2) Look up cot at Dictionary.com
"hut, cottage;" see cote.
cotangent (n.) Look up cotangent at Dictionary.com
a contraction of co. tangent, abbreviation of complement + tangent (n.).
cote (n.) Look up cote at Dictionary.com
Old English cote, fem. of cot (plural cotu) "small house, bedchamber, den" (see cottage). Applied to buildings for animals from early 15c.
coterie (n.) Look up coterie at Dictionary.com
1738, from French coterie "circle of acquaintances," originally in Middle French an organization of peasants holding land from a feudal lord (14c.), from cotier "tenant of a cote" (see cottage).
coterminous (adj.) Look up coterminous at Dictionary.com
1630s, malformed in English from co- + terminous (see terminal). Latin purists prefer conterminous.
cotillion (n.) Look up cotillion at Dictionary.com
type of dance, 1766, from French cotillion (15c.), originally "petticoat," a double diminutive of Old French cote "skirt" (see coat (n.)); its application to a kind of dance arose in France and is considered obscure by some linguists, but there are lively turns in the dance that flash the petticoats.

Meaning "formal ball" is 1898, American English, short for cotillion ball. French uses -on (from Latin -onem) to reinforce Latin nouns felt to need more emphatic power (as in poisson from Latin piscis). It also uses -on to form diminutives, often strengthened by the insertion of -ill-, as in the case of this word.