Online Etymology Dictionary

coruscation (n.): late 15c., from Latin coruscationem (nominative coruscatio), noun of action from past participle stem of coruscare "to vibrate, glitter."
corvee (n.): 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 com- "with" (see com-) + rogare "to ask" (see rogation).
corvette (n.): 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: 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.): 1630s, from medical Latin, from Greek koryza "running at the nose."
cosa nostra: 1963, "the Mafia in America," from Italian, literally "this thing of ours."
cosecant (n.): 1706, from co, short for complement, + secant.
cosh (n.): "stout stick," 1869, of unknown origin.
cosher (n.): 1630s, phonetic spelling of Irish coisir "feast, entertainment."
cosign (v.): also co-sign, by 1944, from co- + sign (v.). Related: Cosigned; cosigning.
cosigner (n.): also co-signer, 1946, agent noun from cosign; earlier in this sense was cosignatory (1865).
cosine (n.): 1630s, from co. sinus, abbreviation of Medieval Latin complementi sinus (see complement + sine).
cosmetic (n.): 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.): 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.): 1926, American English, from cosmetology + -ist. Won out over cosmetician.
cosmetology (n.): 1855, from French cosmétologie, from Latinized form of Greek kosmetos (see cosmetic) + -ology.
cosmic (adj.): 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-: 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.): 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."
cosmography (n.): "description of the universe," mid-15c., from cosmo- + -graphy. Related: Cosmographic.
cosmological (adj.): 1825, from cosmology + -ical.
cosmology (n.): 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.): 1959, Anglicization of Russian kosmonavt, ultimately from Greek kosmos (see cosmos) + nautes "sailor" (see naval).
cosmopolitan (adj.): 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.): 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.): 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" (cf. 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.): 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.): 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." Related: Coseted; coseting. Cf. German Hauslamm, Italian casiccio.
cost (n.): 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" (see stet).
cost (v.): late 14c., from Old French coster (Modern French coûter) "to cost," from cost (see cost (n.)).
cost-effective (adj.): also cost effective, 1967, from cost (n.) + effective.
costa (n.): 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.): "pertaining to the ribs," 1630s, from French costal (16c.), from Medieval Latin costalis, from costa "a rib" (see coast (n.)).
costard (n.): 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.): 1510s, "itinerant apple-seller" from coster (see costard) + monger. 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.): c.1400, from Middle French costivé, from Latin constipatus, past participle of constipare (see constipation).
costly (adj.): late 14c., from cost + -ly (1). Earlier formation with the same sense were costful (mid-13c.), costious (mid-14c.).
costume (n.): 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.
costume (v.): 1823, from costume (n.). Related: Costumed; costuming.
cosy (adj.): chiefly British form of cozy.
cot (n.1): "small bed," 1630s, from Hindi khat "couch, hammock," from Sanskrit khatva, probably from a Dravidian source (cf. Tamil kattil "bedstead").
cot (n.2): "hut, cottage;" see cote.
cotangent (n.): from co. tangent, abbreviation of complement + tangent.
cote (n.): Old English cote, fem. of cot (plural cotu) "small house, bedchamber, den" (see cottage). Applied to buildings for animals from early 15c.
coterie (n.): 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.): 1630s, malformed in English from co- + terminous (see terminal). Latin purists prefer conterminous.
cotillion (n.): 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 (e.g. 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.
cotquean (n.): 1540s, obsolete, "housewife of a cot," from cot (see cottage) + quean; hence "a vulgar beldam, scold" [OED]; also used contemptuously (by Shakespeare, etc.) of men seen as overly interested in housework.
cottage (n.): late 13c., from Old French cote "hut, cottage" + Anglo-French suffix -age (probably denoting "the entire property attached to a cote"). Old French cot is probably from Old Norse kot "hut," cognate of Old English cot, cote "cottage, hut," from Proto-Germanic *kutan (cf. Middle Dutch cot, Dutch kot).

Meaning "small country residence" (without suggestion of poverty or tenancy) is from 1765. Modern French cottage is a 19c. reborrowing from English. Cottage industry is attested from 1921. Cottage cheese is attested from 1831, American English, earliest in reference to Philadelphia:
There was a plate of rye-bread, and a plate of wheat, and a basket of crackers; another plate with half a dozen paltry cakes that looked as if they had been bought under the old Court House; some morsels of dried beef on two little tea-cup plates: and a small glass dish of that preparation of curds, which in vulgar language is called smear-case, but whose nom de guerre is cottage-cheese, at least that was the appellation given it by our hostess. ["Miss Leslie," "Country Lodgings," Godey's "Lady's Book," July 1831]
cotter (n.): 1640s, perhaps a shortened form of cotterel, a dialectal word for "cotter pin or bolt, bracket to hang a pot over a fire" (1560s), itself of uncertain origin.