Online Etymology Dictionary

conversation (n.): mid-14c., "living together, having dealings with others," also "manner of conducting oneself in the world;" from Old French conversation, from Latin conversationem (nominative conversatio) "act of living with," noun of action from past participle stem of conversari "to live with, keep company with," literally "turn about with," from Latin com- "with" (see com-) + versare, frequentative of vertere (see versus).

Specific sense of "talk" is 1570s. Used as a synonym for "sexual intercourse" from at least 1511, hence criminal conversation, legal term for adultery from late 18c. Related: Conversationalist; conversationist.
conversational (adj.): 1779, from conversation + -al (1).
converse (v.): "to communicate (with)," 1590s; earlier "to move about, live, dwell" (mid-14c.), from Old French converser "to talk" (12c.), from Latin conversari (see conversation). Related: Conversed; conversing.
converse (adj.): "exact opposite," 1560s, from Latin conversus "turn around," past participle of convertere "to turn about" (see convert). Originally mathematical. The noun is attested from 1550s in mathematics. Related: Conversely.
conversion (n.): mid-14c., originally of religion, from French conversion, from Latin conversionem (nominative conversatio), noun of action from past participle stem of convertere (see convert (v.)). General sense of "transformation" is early 15c. Of buildings, from 1921. Conversion disorder "hysteria" (attested from 1946 but said to have been coined by Freud) was in DSM-IV (1994).
convert (v.): c. 1300, from Old French convertir, from Vulgar Latin *convertire, from Latin convertere "turn around, transform," from com- "together" (see com-) + vertere "to turn" (see versus). Originally in the religious sense. The Latin word is glossed in Old English by gecyrren, from cierran "to turn, return." Related: Converted; converting.
convert (n.): 1560s, from convert (v.). Earlier was convers (early 14c.).
converter (n.): 1530s, agent noun from convert (v.). Of machinery, from 1867.
convertible (adj.): late 14c., from Old French convertible (13c.), from Late Latin convertibilis "changeable," from Latin convertere (see convert (v.)). The noun is recorded from 1610s; meaning "automobile with a fold-down top" is from 1916.
convex (adj.): 1570s, from Middle French convexe, from Latin convexus "vaulted, arched," past participle of convehere "to bring together," from com- "together," or "thoroughly" (see com-) + vehere "to bring" (see vehicle). Possibly from the idea of vaults carried together to meet at the point of a roof. Related: Convexity. Convex lens is from 1822.
convey (v.): c. 1300, "to go along with;" late 14c., "to carry, transport;" from Anglo-French conveier, from Old French convoier "to escort" (Modern French convoyer), from Vulgar Latin *conviare "to accompany on the way," from Latin com- "together" (see com-) + via "way, road" (see via). It was a euphemism for "steal" 15c.-17c., which helped broaden its meaning. Related: Conveyed; conveying.
conveyance (n.): mid-15c., "act of conveying," from convey + -ance. Meaning "document by which something is legally conveyed" is from 1570s; sense "means of transportation" is attested from 1590s. Related: Conveyanced; conveyancing.
conveyer (n.): 1510s, agent noun from convey. Latinate form conveyor is later (1640s).
convict (v.): mid-14c., from Latin convictus, past participle of convincere "to 'overcome' in argument" (see convince). Replaced Old English verb oferstælan. Related: Convicted; convicting.
convict (n.): late 15c., from convict (v). Slang shortening con is from 1893.
conviction (n.): mid-15c., "the proving of guilt," from Late Latin convictionem (nominative convictio) "proof, refutation," noun of action from past participle stem of convincere (see convince). Meaning "mental state of being convinced" is from 1690s; that of "firm belief, a belief held as proven" is from 1841.
convictions (n.): "those ideas which one believes to be true," 1883, plural of conviction.
convince (v.): 1520s, "to overcome in argument," from Latin convincere "to overcome decisively," from com-, intensive prefix (see com-), + vincere "to conquer" (see victor). Meaning "to firmly persuade" is from c. 1600. Related: Convinced; convincing; convincingly.
convival (adj.): 1640s, from Latin convivalis, from conviva, from convivere (see convivial). Has been replaced in most uses by convivial.
convive (n.): 1640s, from French convive, from Latin conviva "one who feasts with others," from convivere (see convivial). In mid-19c., also "woman 'who lives in the same house with a number of others.' "
convivial (adj.): 1660s, "pertaining to a feast," from Late Latin convivialis, from Latin convivium "a feast," from convivere "to carouse together," from com- "together" (see com-) + vivere "to live" (see vital). Meaning "sociable" is from 18c. Related: Conviviality.
convocate (v.): mid-16c., from Latin convocatus, past participle of convocare (see convocation).
convocation (n.): late 14c., "assembly of persons," from Old French convocation and directly from Latin convocationem (nominative convocatio), noun of action from past participle stem of convocare "to call together," from com- "together" (see com-) + vocare "to call," from vox "voice" (see voice (n.)). Related: Convocational.
convoke (v.): 1590s, from Middle French convoquer (14c.), from Latin convocare "to call together" (see convocation). Related: Convoked; convoking.
convolute (adj.): "rolled up together," 1794, from Latin convolutus, past participle of convolvere (see convolution). The noun meaning "something convoluted" is from 1846.
convoluted (adj.): 1811, past participle adjective from verb convolute (1690s), from Latin convolutus, past participle of convolvere (see convolution); or perhaps a back-formation from convolution. French has convoluté (18c.), in form a past participle adjective, without the verb.
convolution (n.): 1540s, from Latin convolutus, past participle of convolvere "to roll together," from com- "together" (see com-) + volvere "to roll" (see volvox).
convoy (n.): early 16c., "the act of guiding or escorting for protection," from convoy (v.), late 14c., from Old French convoier, from Vulgar Latin *conviare, literally "go together on the road" (see convey). The meaning "train of ships or wagons carrying munitions or provisions in wartime under protection of escort" is from c. 1600.
convulse (v.): 1640s, transitive; 1680s, intransitive; from Latin convulsus, past participle of convellere (transitive only) "to pull away, to pull this way and that, wrench," hence "to weaken, overthrow, destroy" (see convulsion). Related: Convulsed (1630s); convulsing.
convulsion (n.): 1580s, from Latin convulsionem (nominative convulsio), noun of action from past participle stem of convellere "to tear loose," from com- "together" (see com-) + vellere "to pluck, pull violently" (see svelte).
convulsive (adj.): 1610s, from French convulsif, from Medieval Latin *convulsivus, from convulsus, past participle of convellere (see convulse (v.)). Related: Convulsively.
cony (n.): see coney.
coo (v.): 1660s, echoic of doves; the phrase to bill and coo is first recorded 1816. Related: Cooing. The noun is recorded from 1729.
cooch (n.): "vagina," slang, c.2003, short for coochie.
coochie (n.): "vagina," slang, by 1991, perhaps from hoochie-coochie, especially in the blues song "Hoochie Coochie Man" by Willie Dixon (1954), featuring a sexually suggestive phrase that traces at least to the 1893 World's Fair (see hoochy koochy).
cook (n.): Old English coc, from Vulgar Latin cocus "cook," from Latin coquus, from coquere "to cook, prepare food, ripen, digest, turn over in the mind" from PIE root *pekw- "to cook" (source also of Oscan popina "kitchen," Sanskrit pakvah "cooked," Greek peptein, Lithuanian kepti "to bake, roast," Old Church Slavonic pecenu "roasted," Welsh poeth "cooked, baked, hot"). Germanic languages had no one native term for all types of cooking, and borrowed the Latin word (Old Saxon kok, Old High German choh, German Koch, Swedish kock).
There is the proverb, the more cooks the worse potage. [Gascoigne, 1575]
cook (v.): late 14c., from cook (n.); the figurative sense of "to manipulate, falsify, doctor" is from 1630s. Related: Cooked, cooking. To cook with gas is 1930s jive talk.
cookbook (n.): 1809, from cook + book (n.). Earlier was cookery book (1630s).
cooker (n.): type of stove, 1884, from cook (v.) + -er (1).
cookery (n.): late 14c.; see cook (n.) + -ery.
cookie (n.): 1703, American English, from Dutch koekje "little cake," diminutive of koek "cake," from Middle Dutch koke (see cake (n.)). Slang application to persons attested since 1920. Phrase that's the way the cookie crumbles "that's the way things happen" is from 1957.
cookout (n.): also cook-out, 1930, American English, from cook (v.) + out (adv.).
cooky (n.): variant of cookie.
cool (adj.): Old English col "not warm" (but usually not as severe as cold), also, of persons, "unperturbed, undemonstrative," from Proto-Germanic *koluz (source also of Middle Dutch coel, Dutch koel, Old High German kuoli, German kühl "cool," Old Norse kala "be cold"), from PIE root *gel- "cold, to freeze" (see cold (adj.)).

Applied since 1728 to large sums of money to give emphasis to amount. Meaning "calmly audacious" is from 1825. Slang use for "fashionable" is 1933, originally African-American vernacular; modern use as a general term of approval is from late 1940s, probably from bop talk and originally in reference to a style of jazz; said to have been popularized in jazz circles by tenor saxophonist Lester Young. Related: Coolly.
cool (n.): c. 1400, "coldness, coolness," from cool (adj.). Meaning "one's self-control, composure" (the thing you either keep or lose) is from 1966.
cool (v.): Old English colian, "to lose warmth," also figuratively, "to lose ardor," from the root of cool (adj.). Meaning "to cause to lose warmth" is from late 14c. Related: Cooled; cooling.
coolant (n.): "radiator fluid," 1930, from cool (adj.) + -ant.
cooler (n.): 1570s, "a vessel in which something is set to cool," agent noun from cool (v.). Meaning "insulated box to keep things cool" is from 1958. Slang meaning "jail" is attested from 1884.
coolie (n.): name given by Europeans to hired laborers in India and China, c. 1600, from Hindi quli "hired servant," probably from kuli, name of an aboriginal tribe or caste in Gujarat. The name was picked up by the Portuguese, who used it in southern India (where by coincidence kuli in Tamil meant "hire") and in China.
coolness (n.): Old English colnesse; see cool (adj.) + -ness. Figurative sense of "calmness" is from 1650s; that of "absence of warm affection" is from 1670s.