cn- Look up cn- at Dictionary.com
consonant group used in Old English (the Clark Hall dictionary has 82 entries under cn-) but in Middle English all lost or turned to kn-. Also common in Greek, and retained in the spelling of some English words from Greek but not now admitted in speech, the n- only being sounded.
Cnidaria (n.) Look up Cnidaria at Dictionary.com
phylum of stinging invertebrates, from Latinized form of Greek knide "nettle," from stem of knizein "to scratch scrape," + abstract noun ending -ia. Related: Cnidarian.
co- Look up co- at Dictionary.com
in Latin, the form of com- in compounds with stems beginning in vowels and h- and gn- (see com-). Taken in English from 17c. as a living prefix meaning "together, mutually, in common," and used promiscuously with native words and Latin-derived words not beginning with vowels, sometimes even with words already having it (such as co-conspiritor).
co-ed (n.) Look up co-ed at Dictionary.com
also coed, 1886, American English, (first in Louisa Mae Alcott's "Jo's Boys"); short for "co-educational system;" 1889 as an adjective, short for coeducational; 1893 as a noun meaning "girl or woman student at a co-educational institution."
co-op (n.) Look up co-op at Dictionary.com
1861, abbreviation of cooperative. The hyphen is needed to avoid confusion with coop (n.).
co-opt (v.) Look up co-opt at Dictionary.com
1650s, "to select (someone) for a group or club by a vote of members," from Latin cooptare "to elect, to choose as a colleague or member of one's tribe," from com- "together" (see com-) + optare "choose" (see option (n.)). For some reason this defied the usual pattern of Latin-to-English adaptation, which should have yielded *cooptate. Sense of "take over" is first recorded c. 1953. Related: Co-opted; co-opting.
co-ordinate Look up co-ordinate at Dictionary.com
see coordinate.
co-star Look up co-star at Dictionary.com
also costar, 1919 as a verb; 1926 as a noun, from co- + star (v.).
co. Look up co. at Dictionary.com
abbreviation of company, attested by 1670s.
coach (v.) Look up coach at Dictionary.com
1610s, "to convey in a coach," from coach (n.). Meaning "to prepare (someone) for an exam" is from 1849. Related: Coached; coaching.
coach (n.) Look up coach at Dictionary.com
1550s, "large kind of carriage," from Middle French coche (16c.), from German kotsche, from Hungarian kocsi (szekér) "(carriage) of Kocs," village where it was first made. In Hungary, the thing and the name for it date from 15c., and forms are found in most European languages (Spanish and Portuguese coche, Italian cocchino, Dutch koets). Applied to railway cars 1866, American English. Sense of "economy or tourist class" is from 1949.

Meaning "instructor/trainer" is c. 1830 Oxford University slang for a tutor who "carries" a student through an exam; athletic sense is from 1861. A more classical word for an athletic trainer was agonistarch, from Greek agonistarkhes "one who trains (someone) to compete in the public games and contests."
coachman (n.) Look up coachman at Dictionary.com
1570s, from coach (n.) + man (n.).
coagulant (n.) Look up coagulant at Dictionary.com
1770, from Latin coagulantem (nominative coagulans), present participle of coagulare (see coagulate).
coagulate (v.) Look up coagulate at Dictionary.com
early 15c., from Latin coagulatus, past participle of coagulare "to cause to curdle," from cogere "to curdle, collect" (see cogent). Earlier coagule, c. 1400, from Middle French coaguler. Related: Coagulated; coagulating.
coagulation (n.) Look up coagulation at Dictionary.com
c. 1400, from Latin coagulationem (nominative coagulatio), noun of action from past participle stem of coagulare (see coagulate).
coal (n.) Look up coal at Dictionary.com
Old English col "charcoal, live coal," from Proto-Germanic *kula(n) (source also of Old Frisian kole, Middle Dutch cole, Dutch kool, Old High German chol, German Kohle, Old Norse kol), from PIE root *g(e)u-lo- "live coal" (source also of Irish gual "coal").

Meaning "mineral consisting of fossilized carbon" is from mid-13c. First mentioned (370 B.C.E.) by Theophrastus in his treatise "On Stones" under the name lithos anthrakos (see anthrax). Traditionally good luck, coal was given as a New Year's gift in England, said to guarantee a warm hearth for the coming year. The phrase drag (or rake) over the coals was a reference to the treatment meted out to heretics by Christians. To carry coals "do dirty work," also "submit to insult" is from 1520s. To carry coals to Newcastle "add to that of which there is already an abundance" (c. 1600) is a local variant on an ancient class of expression: Latin had in litus harenas fundere "pour sand on the beach;" Greek glauk eis Athenas "owls to Athens."
coalesce (v.) Look up coalesce at Dictionary.com
1540s, from Latin coalescere "unite, grow together, become one in growth," from com- "together" (see co-) + alescere "be nourished," hence, "increase, grow up," inchoative of alere "to suckle, nourish," from PIE root *al- (2) "to grow, nourish." Related: Coalesced; coalescing; coalescence; coalescent.
coalition (n.) Look up coalition at Dictionary.com
1610s, "the growing together of parts," from French coalition (1540s), from Late Latin coalitus "fellowship," originally past participle of Latin coalescere "unite, grow together, become one in growth" (see coalesce). First used in a political sense 1715.
coaming (n.) Look up coaming at Dictionary.com
1610s, nautical, of unknown origin.
coarse (adj.) Look up coarse at Dictionary.com
early 15c., cors "ordinary" (modern spelling is from late 16c.), probably adjectival use of noun cours (see course (n.)), originally referring to rough cloth for ordinary wear. Developed a sense of "rude" c. 1500 and "obscene" by 1711. Perhaps related, via metathesis, to French gros, which had a similar sense development. Related: Coarsely; coarseness.
coarsen (v.) Look up coarsen at Dictionary.com
1805, from coarse + -en (2). Related: Coarsened; coarsening.
coast (v.) Look up coast at Dictionary.com
late 14c., "to skirt, to go around the sides, to go along the border" of something (as a ship does the coastline), from Anglo-French costien, from the French source of coast (n.). The meaning "sled downhill," first attested 1775 in American English, is a separate borrowing. Of motor vehicles, "to move without thrust from the engine," by 1925; figurative use, of persons, "not to exert oneself," by 1934. Related: Coasted; coasting.
coast (n.) Look up coast at Dictionary.com
"margin of the land," early 14c.; earlier "rib as a part of the body" (early 12c.), from Old French coste "rib, side, flank; slope, incline;" later "coast, shore" (12c., Modern French côte), from Latin costa "a rib," perhaps related to a root word for "bone" (compare Old Church Slavonic kosti "bone," and PIE root *ost-).

Latin costa developed a secondary sense in Medieval Latin of "the shore," via notion of the "side" of the land, as well as "side of a hill," and this passed into Romanic (Italian costa "coast, side," Spanish cuesta "slope," costa "coast"), but only in the Germanic languages that borrowed it is it fully specialized in this sense (Dutch kust, Swedish kust, German Küste, Danish kyst). French also used this word for "hillside, slope," which led to verb meaning "sled downhill," first attested 1775 in American English. Expression the coast is clear (16c.) is an image of landing on a shore unguarded by enemies.
coastal (adj.) Look up coastal at Dictionary.com
1883, from coast (n.) + -al (1). The proper Latin form costal is used only of ribs.
coaster (n.) Look up coaster at Dictionary.com
1570s, "one who sails along coasts," agent noun from coast (v.) in its original sense "to go around the sides or border" of something. Applied to vessels for such sailing from 1680s. Tabletop drink stand (c. 1887), originally "round tray for a decanter," so called from a resemblance to a sled, or because it "coasted" around the perimeter of the table to each guest in turn after dinner.
coastline (n.) Look up coastline at Dictionary.com
1860, from coast (n.) + line (n.).
coat (v.) Look up coat at Dictionary.com
late 14c., "to provide with a coat," from coat (n.). Meaning "to cover with a substance" is from 1753. Related: Coated; coating.
coat (n.) Look up coat at Dictionary.com
early 14c., "outer garment," from Old French cote "coat, robe, tunic, overgarment," from Frankish *kotta "coarse cloth" or some other Germanic source (compare Old Saxon kot "woolen mantle," Old High German chozza "cloak of coarse wool," German Kotze "a coarse coat"), of unknown origin. Transferred to animal's natural covering late 14c. Extended 1660s to a layer of any substance covering any surface. Spanish, Portuguese cota, Italian cotta are Germanic loan-words.
coat of arms (n.) Look up coat of arms at Dictionary.com
mid-14c., originally a tunic embroidered with heraldic arms (worn over armor, etc); see coat (n.) + arm (n.2) and compare Old French cote a armer. Sense transferred to the heraldic arms themselves by 1560s. Hence turncoat, one who put his coat on inside-out to hide the badge of his loyalty.
coati (n.) Look up coati at Dictionary.com
Brazilian raccoon, 1670s, from Tupi (Brazil), from cua "belt, cincture" + tim "nose."
coating (n.) Look up coating at Dictionary.com
"layer over a surface," 1768, verbal noun from coat (v.).
coattails (n.) Look up coattails at Dictionary.com
also coat-tail, c. 1600, from coat (n.) + tail (n.). In 17c., to do something on one's own coattail meant "at one's own expense. Meaning "power of one person," especially in politics, is from 1848 (in a Congressional speech by Abraham Lincoln, in reference to Andrew Jackson); expression riding (someone's) coattails into political office is from 1949.
coauthor (n.) Look up coauthor at Dictionary.com
also co-author, from co- + author. From 1948 as a verb. Related: Coauthored; coauthoring.
coax (v.) Look up coax at Dictionary.com
1580s, originally in slang phrase to make a coax of, from earlier noun coax, cox, cokes "a fool, ninny, simpleton" (1560s); modern spelling is 1706. Origin obscure, perhaps related to cock (n.1). Related: Coaxed; coaxing.
coaxial (adj.) Look up coaxial at Dictionary.com
"having a common axis," 1904, as a term in mathematics; coaxial cable is 1934. See co- + axial.
cob (n.) Look up cob at Dictionary.com
a word or set of identical words with a wide range of meanings, many seeming to derive from notions of "heap, lump, rounded object," also "head" and its metaphoric extensions. With cognates in other Germanic languages; of uncertain origin and development. "The N.E.D. recognizes eight nouns cob, with numerous sub-groups. Like other monosyllables common in the dial[ect] its hist[ory] is inextricable" [Weekley]. In the 2nd print edition, the number stands at 11. Some senses are probably from Old English copp "top, head," others probably from Old Norse kubbi or Low German, all perhaps from a Proto-Germanic base *kubb- "something rounded." Among the earliest attested English senses are "headman, chief," and "male swan," both early 15c., but the surname Cobb (1066) suggests Old English used a form of the word as a nickname for "big, leading man." The "corn shoot" sense is attested by 1680s.
cobalt (n.) Look up cobalt at Dictionary.com
1680s, from German kobold "household goblin" (13c.), which became also a Harz Mountains silver miners' term for rock laced with arsenic and sulfur (so called because it degraded the ore and made the miners ill), from Middle High German kobe "hut, shed" + *holt "goblin," from hold "gracious, friendly," a euphemistic word for a troublesome being. The metallic element was extracted from this rock. It was known to Paracelsus, but discovery is usually credited to the Swede George Brandt (1733), who gave it the name. Extended to a blue color 1835 (a mineral containing it had been used as a blue coloring for glass since 16c.). Compare nickel.
cobble (n.) Look up cobble at Dictionary.com
"paving stone; worn, rounded stone," c. 1600, earlier cobblestone, probably a diminutive of cob in some sense. The verb in this sense is from 1690s. Related: Cobbled; cobbling.
cobble (v.) Look up cobble at Dictionary.com
"to mend clumsily," late 15c., perhaps a back-formation from cobbler (n.1), or from cob, via a notion of lumps. Related: Cobbled; cobbling.
cobbler (n.1) Look up cobbler at Dictionary.com
late 13c., cobelere "one who mends shoes," of uncertain origin. It and cobble (v.) "evidently go together etymologically" [OED], but the historical record presents some difficulties. "The cobbler should stick to his last" (ne sutor ultra crepidam) is from the anecdote of Greek painter Apelles.
On one occasion a cobbler noticed a fault in the painting of a shoe, and remarking upon it to a person standing by, passed on. As soon as the man was out of sight Apelles came from his hiding-place, examined the painting, found that the cobbler's criticism was just, and at once corrected the error. ... The cobbler came by again and soon discovered that the fault he had pointed out had been remedied; and, emboldened by the success of his criticism, began to express his opinion pretty freely about the painting of the leg! This was too much for the patience of the artist, who rushed from his hiding place and told the cobbler to stick to his shoes. [William Edward Winks, "Lives of Illustrious Shoemakers," London, 1883]
[The quote is variously reported: Pliny ("Natural History" XXXV.x.36) has ne supra crepidam judicaret, while Valerius Maximus (VIII.xiii.3) gives supra plantam ascendere vetuit.]
cobbler (n.2) Look up cobbler at Dictionary.com
"deep-dish fruit pie," 1859, American English, perhaps related to 14c. cobeler "wooden bowl."
cobblestone (n.) Look up cobblestone at Dictionary.com
late 14c., kobilstane; see cobble (n.) + stone (n.).
COBOL (n.) Look up COBOL at Dictionary.com
1960, U.S. Defense Department acronym, from "Common Business-Oriented Language."
cobra (n.) Look up cobra at Dictionary.com
1802, short for cobra capello (1670s), from Portuguese cobra de capello "serpent (of the hood)," from Latin colubra "a snake, female serpent" (source of French couleuvre "adder"), which is of uncertain origin. So called for the expandable loose skin about its neck. The word came to English via Portuguese colonies in India, where the native name is nag (see naga).
cobweb (n.) Look up cobweb at Dictionary.com
early 14c., coppewebbe; the first element is Old English -coppe, in atorcoppe "spider," literally "poison-head" (see attercop). Spelling with -b- is from 16c., perhaps from cob. Cob as a stand-alone for "a spider" was an old word nearly dead even in dialects when J.R.R. Tolkien used it in "The Hobbit" (1937).
coca (n.) Look up coca at Dictionary.com
South American plant, 1570s, from Spanish coca, from Quechua cuca, which is perhaps ultimately from Aymara, a native language of Bolivia.
Coca-Cola Look up Coca-Cola at Dictionary.com
invented 1886 in Atlanta, Georgia, U.S., by druggist Dr. John S. Pemberton. So called because original ingredients were derived from coca leaves and cola nuts. It contained minute amounts of cocaine until 1909.
Drink the brain tonic and intellectual soda fountain beverage Coca-Cola. [Atlanta "Evening Journal," June 30, 1887]
Coca-colanization, also Coca-colonization coined 1950 during an attempt to ban the beverage in France, led by the communist party and the wine-growers.
France's Communist press bristled with warnings against US "Coca-Colonization." Coke salesmen were described as agents of the OSS and the U.S. State Department. "Tremble," roared Vienna's Communist Der Abend, "Coca-Cola is on the march!" [Time Magazine, 1950]
Coca-colonialism attested by 1956.
cocaine (n.) Look up cocaine at Dictionary.com
1874, from Modern Latin cocaine (1856), coined by Albert Niemann of Gottingen University from coca (from Quechua cuca) + chemical suffix -ine (2). A medical coinage, the drug was used 1870s as a local anaesthetic for eye surgery, etc. "It is interesting to note that although cocaine is pronounced as a disyllabic word it is trisyllabic in its formation." [Flood]
cocci (n.) Look up cocci at Dictionary.com
spherical-shaped bacteria, plural of Latin coccus, from Greek kokkos "berry" (see cocco-).
coccidiosis (n.) Look up coccidiosis at Dictionary.com
Modern Latin, from Greek *kokkidion, diminutive of kokkis, diminutive of kokkos "berry" + -osis.