Online Etymology Dictionary

coerce (v.): mid-15c., cohercen, from Middle French cohercer, from Latin coercere "to control, restrain, shut up together," from com- "together" (see co-) + arcere "to enclose, confine, contain, ward off," from PIE *ark- "to hold, contain, guard" (see arcane). Related: Coerced; coercing. No record of the word between late 15c. and mid-17c.; its reappearance 1650s is perhaps a back-formation from coercion.
coercion (n.): early 15c., from Old French cohercion (Modern French coercion), from Medieval Latin coercionem, from Latin coerctionem, earlier coercitionem, noun of action from past participle stem of coercere (see coerce).
coercive (adj.): c.1600, from coerce + -ive. Form coercitive (attested from 1630s) is more true to Latin.
coetaneous (adj.): "having the same age," c.1600, from Late Latin coaetanus "one of the same age," from com- "with, together with" (see co-) + aetat- "age" + adjectival suffix -aneus.
coeval (adj.): "having the same age," formed in English early 17c. from Late Latin coaevus, from Latin com- "equal" (see co-) + aevum "an age" (see eon). As a noun from c.1600.
coevolution (n.): also co-evolution, 1965, from co- + evolution; supposedly introduced by Paul Ehrlich and Peter Raven in a study of the relationship between caterpillars and plants.
coexist (v.): 1670s, from co- + exist. Of political/economic systems (especially with reference to communism and the West) from 1931. Related: Coexisted; coexisting.
coexistence (n.): also co-existence, mid-15c., "joint existence;" see co- + existence. As "peaceful relations between states of different ideologies," 1954, a Cold War term.
coextensive (adj.): 1771, from co- + extensive.
coffee (n.): c.1600, from Italian caffe, from Turkish kahveh, from Arabic qahwah "coffee," said originally to have meant "wine," but perhaps rather from Kaffa region of Ethiopia, a home of the plant (coffee in Kaffa is called buno, which was borrowed into Arabic as bunn "raw coffee"). Much initial diversity of spelling, including chaoua.

Yemen was the first great coffee exporter and to protect its trade decreed that no living plant could leave the country. In 16c., a Muslim pilgrim brought some coffee beans from Yemen and raised them in India. Appeared in Europe (from Arabia) c.1515-1519. Introduced to England by 1650, and by 1675 the country had more than 3,000 coffee houses. Coffee plantations established in Brazil 1727. Meaning "a light meal at which coffee is served" is from 1774. Coffee break attested from 1940s. Coffee pot from 1705.
coffer (n.): mid-13c., from Old French cofre "a chest" (12c., Modern French coffre), from Latin cophinus "basket" (see coffin).
coffin (n.): early 14c., "chest or box for valuables," from Old French cofin "sarcophagus," earlier "basket, coffer" (12c., Modern French coffin), from Latin cophinus "basket, hamper" (source of Italian cafano, Spanish cuebano "basket"), from Greek kophinos "a basket," of uncertain origin.

Funeral sense in English is 1520s; before that it was the literal Latin one and had also a meaning of "pie crust" (late 14c.). Meaning "vehicle regarded as unsafe" is from 1830s. Coffin nail "cigarette" is slang from 1880; nail in (one's) coffin "thing that contributes to one's death" is from 1792.
cog (n.): c.1300, "cog wheel;" late 14c., "tooth on a wheel," probably a borrowing from a Scandinavian language (cf. Norwegian kugg "cog") and cognate with Middle High German kugel "ball."
cogency (n.): 1680s, from cogent + -cy.
cogenial (adj.): 1774, variant of congenial.
cogent (adj.): 1650s, from French cogent "necessary, urgent" (14c.), from Latin cogentem (nominative cogens), present participle of cogere "to curdle; to compel; to collect," literally "to drive together," from com- "together" (see co-) + agere "to drive" (see act (n.)).
cogitate (v.): late 16c., from Latin cogitatus, past participle of cogitare "to think" (see cogitation). Related: Cogitated; cogitating.
cogitation (n.): c.1200, "thought, idea, notion," from Old French cogitacion "thought, consideration, reflection," from Latin cogitationem (nominative cogitatio), noun of action from past participle stem of cogitare "to think, reflect, consider, turn over in the mind," apparently from co-agitare, from com- "together" (see co-) + agitare, here in a sense of "to turn over in the mind," literally "to put in constant motion, drive, impel," frequentative of agere "to move, drive" (see agitation).
cogitative (adj.): late 15c., from Old French cogitatif (14c.), from Medieval Latin cogitativus, from Latin cogitare (see cogitation).
cognac (n.): 1590s, Coniacke, "wine produced in Cognac," the region in western France. The sense of "brandy" is 1755, shortened from 17c. cognac brandy, which was distilled from cognac wine. The place name is from Medieval Latin Comniacum, from the personal name Cominius and the Gallo-Roman suffix -acum.
cognate (adj.): 1640s, from Latin cognatus "of common descent," from com- "together" (see co-) + gnatus, past participle of gnasci, older form of nasci "to be born" (see genus). Words that are cognates are cousins, not siblings. As a noun, from 1754.
cognisance (n.): alternative spelling of cognizance (q.v.); also see -ize.
cognisant (adj.): alternative spelling of cognizant (q.v.); also see -ize.
cognition (n.): mid-15c., "ability to comprehend," from Latin cognitionem (nominative cognitio) "a getting to know, acquaintance, knowledge," noun of action from past participle stem of cognoscere (see cognizance).
cognitive (adv.): 1580s, from Latin cognit-, past participle stem of cognoscere (see cognizance) + -ive. Taken over by psychologists and sociologists after c.1940. Related: Cognitively.
cognitive dissonance (n.): 1957, developed and apparently coined by U.S. social psychologist Leon Festinger (1919-1989).
cognizable (adj.): 1670s, "capable of being known," also "liable to be tried in a given court or jurisdiction," from stem of cognizance + -able.
cognizance (n.): mid-14c., from Anglo-French conysance "recognition," later, "knowledge," from Old French conoissance "acquaintance, recognition; knowledge, wisdom" (Modern French connaissance), from past participle of conoistre "to know," from Latin cognoscere "to get to know, recognize," from com- "together" (see co-) + gnoscere "to know" (see notice). The -g- was restored in English spelling 15c. and has gradually affected the pronunciation, which was always "con-." The old pronunciation lingered longest in legal use.
cognizant (adj.): 1820, back-formation from cognizance.
cognize (v.): 1650s, back-formation from cognizance. Related: Cognized; cognizing.
cognomen (n.): 1809, from Latin com- "with" (see co-) + (g)nomen "name" (see name (n.)). Third or family name of a Roman citizen (Caius Julius Cæsar).
cognoscence (n.): mid-15c., from Latin cognoscere "to know" (see cognizance).
cognoscente (n.): "connoisseur," 1778, from Italian cognoscente, Latinized from conoscente "connoisseur," literally "knowing man," from Latin cognoscentum (nominative cognoscens), present participle of cognoscere "to know" (see cognizance).
cognoscenti (n.): plural of cognoscente (q.v.).
cohabit (v.): euphemism since 1530s to describe a couple living together without benefit of marriage; back-formation from cohabitation. Related: Cohabited; cohabiting.
cohabitate (v.): 1630s, from Late Latin cohabitatus, past participle of cohabitare (see cohabitation). Related: Cohabitated; cohabitating.
cohabitation (n.): mid-15c., "action or state of living together (especially as husband and wife)," from Middle French cohabitation (Old French cohabitacion "cohabitation, sexual intercourse"), from Late Latin cohabitationem (nominative cohabitatio), noun of action from past participle stem of cohabitare "to dwell together," from co- "with, together" (see co-) + habitare "to live, dwell" (see habitat).
Cohen: Jewish surname indicating priestly descent, from Hebrew kohen "priest," from base of kihen "he acted as priest," related to Arabic kahana "he divined, prophesied."
cohere (v.): 1590s, from Latin cohaerere "to cleave together," in transferred use, "be coherent or consistent," from com- "together" (see co-) + haerere "to stick" (see hesitation). Related: Cohered; cohering.
coherence (n.): late 16c., from Middle French cohérence (16c.), from Latin cohaerentia, noun of state from cohaerentem (see coherent). Related: Coherency.
coherent (adj.): 1550s, from Middle French cohérent (16c.), from Latin cohaerentem (nominative cohaerens), present participle of cohaerere "cohere," from com- "together" (see co-) + haerere "to stick" (see hesitation).
cohesion (n.): 1670s, from French cohésion, from Latin cohaesionem (nominative cohaesio) "a sticking together," noun of action from past participle stem of cohaerere "to stick together" (see cohere).
cohesive (adj.): c.1730 (implied in cohesiveness), from Latin cohaes-, past participle stem of cohaerere (see cohere) + -ive. Related: Cohesively.
cohort (n.): early 15c., "company of soldiers," from Middle French cohorte (14c.) and directly from Latin cohortem (nominative cohors) "enclosure," meaning extended to "infantry company" in Roman army (a tenth part of a legion) through notion of "enclosed group, retinue," from com- "with" (see co-) + root akin to hortus "garden," from PIE *ghr-ti-, from root *gher- "to grasp, enclose" (see yard (n.1)). Sense of "accomplice" is first recorded 1952, American English, from meaning "group united in common cause" (1719).
coif (n.): late 13c., "close-fitting cap," from Old French coife "skull-cap, cap worn under a helmet, headgear" (12c., Modern French coiffe), from Late Latin coifa "a cap, hood" (source of Italian cuffia, Spanish cofia, escofia), of West Germanic origin (cf. Old High German kupphia, Middle High German kupfe "cap").
coif (v.): mid-15c., "to cover with a cap," from Middle French coiffer, from Old French coife (see coif (n.)); sense of "to arrange the hair" is attested in English from 1835. Related: Coifed; coifing.
coiffeur (n.): 1847, from French coiffeur "hairdresser," from coiffer "to dress hair," from Old French coife, originally, "inner part of the helmet" (see coif (n.)). A woman hairdresser would be properly a coiffeuse.
coiffure (n.): "style or fashion of wearing the hair," 1630s, from French coiffure, from coiffer (see coiffeur).
coign (n.): archaic spelling of quoin (q.v.), surviving only in Shakespeare's coign of vantage ("Macbeth" I.vi.), popularized by Sir Walter Scott, properly "a projecting corner" (for observation).
coil (v.): "to wind," 1610s, from Middle French coillir "to gather, pick," from Latin colligere "to gather together" (see collect). Meaning specialized perhaps in nautical usage. Related: Coiled; coiling.