civilization (n.) Look up civilization at Dictionary.com
1704, "law which makes a criminal process civil," from civilize + -ation. Sense of "civilized condition" first recorded 1772, probably from French civilisation, to be an opposite to barbarity and a distinct word from civility. Sense of a particular human society in a civilized condition, considered as a whole over time, is from 1857. Related: Civilizational.
civilize (v.) Look up civilize at Dictionary.com
c. 1600, "to bring out of barbarism," from French civiliser, verb from Old French civil (adj.), from Latin civilis "relating to a citizen, relating to public life, befitting a citizen; popular, affable, courteous," alternative adjectival derivative of civis "townsman" (see city). Meaning "become civilized" is from 1868. Related: Civilized; civilizing.
civilized (adj.) Look up civilized at Dictionary.com
1610s, past participle adjective from civilize.
civilly (adv.) Look up civilly at Dictionary.com
1550s, "with reference to citizenship or civil matters," also "in a well-bred manner;" from civil + -ly (2).
civvy (n.) Look up civvy at Dictionary.com
1889, civvies, short for civilian clothes (see civilian (adj.)); in reference to civilian clothes of military men.
clabber (n.) Look up clabber at Dictionary.com
"mud," 1824, from Irish and Gaelic clabar "mud." Also often short for bonnyclabber.
clachan (n.) Look up clachan at Dictionary.com
"small village" (Scottish and Irish), early 15c., from Gaelic clach (plural clachan) "stone."
clack (v.) Look up clack at Dictionary.com
mid-13c., not in Old English, from Old Norse klaka "to chatter," of echoic origin; compare Dutch klakken "to clack, crack," Old High German kleken, French claquer "to clap, crack (see claque). Related: Clacked; clacking.
clack (n.) Look up clack at Dictionary.com
mid-15c., from clack (v.).
clad (adj.) Look up clad at Dictionary.com
"clothed," c. 1300, mid-13c., from clad, alternative past tense and past participle of clothe. Old English had geclæþd, past participle of clæþan.
claddagh Look up claddagh at Dictionary.com
in Claddagh ring (Irish fáinne Chladach), from village of Claddagh, County Gallway. The village name is literally "stony beach."
clade (n.) Look up clade at Dictionary.com
"group of organisms evolved from a common ancestor," 1957, from Greek klados "young branch, offshoot of a plant, shoot broken off," from PIE *kele-, possibly from root *kel- (1) "to strike, cut" (see holt).
cladism (n.) Look up cladism at Dictionary.com
1966, from clade + -ism. Related: Cladist.
cladistic (adj.) Look up cladistic at Dictionary.com
1960, from clade + -istic. Related: Cladistics "systematic classification of life forms" (1965; see -ics).
claim (n.) Look up claim at Dictionary.com
early 14c., "a demand of a right; right of claiming," from Old French claime "claim, complaint," from clamer (see claim (v.)). Meaning "thing claimed or demanded" is from 1792; specifically "piece of land allotted and taken" (chiefly U.S. and Australia, in reference to mining) is from 1851. Insurance sense is from 1878.
claim (v.) Look up claim at Dictionary.com
c. 1300, "to call, call out; to ask or demand by virtue of right or authority," from accented stem of Old French clamer "to call, name, describe; claim; complain; declare," from Latin clamare "to cry out, shout, proclaim," from PIE root *kele- (2) "to shout." Related: Claimed; claiming.

Meaning "to maintain as true" is from 1864; specific sense "to make a claim" (on an insurance company) is from 1897. Claim properly should not stray too far from its true meaning of "to demand recognition of a right."
claimant (n.) Look up claimant at Dictionary.com
1747, from claim (v.), on model of appellant, defendant, etc., or from French noun use of present participle of clamer.
clair-de-lune (n.) Look up clair-de-lune at Dictionary.com
1877, French, literally "moonlight," also used as "color of moonlight." See clear (adj.) + Luna.
clairaudience (n.) Look up clairaudience at Dictionary.com
1864, formed on model of clairvoyance (with French clair; see clear (adj.)) + audience.
Claire Look up Claire at Dictionary.com
fem. proper name, from French claire, fem. of clair literally "light, bright," from Latin clarus "clear, bright, distinct" (see clear (adj.); also compare Clara).
clairvoyance (n.) Look up clairvoyance at Dictionary.com
"paranormal gift of seeing things out of sight," 1837, from special use of French clairvoyance (Old French clerveans, 13c.) "quickness of understanding, sagacity, penetration," from clairvoyant "clear-sighted, discerning, judicious" (13c.), from clair (see clear (adj.)) + voyant "seeing," present participle of voir, from Latin videre "to see" (from PIE root *weid- "to see"). A secondary sense in French is the main sense in English.
clairvoyant (n.) Look up clairvoyant at Dictionary.com
1834 in the psychic sense; see clairvoyant (adj.). Earlier it was used in the sense "clear-sighted person" (1794). Fem. form was Clairvoyante.
clairvoyant (adj.) Look up clairvoyant at Dictionary.com
"having psychic gifts," 1837, earlier "having insight" (1670s), from special use of French clairvoyant "clear-sighted, discerning, judicious" (13c.), from clair (see clear (adj.)) + voyant "seeing," present participle of voir, from Latin videre "to see" (from PIE root *weid- "to see").
clam (v.) Look up clam at Dictionary.com
"to dig for clams," 1630s, American English, from clam (n.). Clam up "be quiet" is 1916, American English, but clam was used in this sense as an interjection mid-14c.
clam (n.) Look up clam at Dictionary.com
bivalve mollusk, c. 1500, in clam-shell, originally Scottish, apparently a particular use from Middle English clam "pincers, vice, clamp" (late 14c.), from Old English clamm "bond, fetter, grip, grasp," from Proto-Germanic *klam- "to press or squeeze together" (source also of Old High German klamma "cramp, fetter, constriction," German Klamm "a constriction"), possibly from a PIE *glem- or *glom- "contain, embrace" (see glebe). If this is right then the original reference is to the shell. Clam-chowder attested from 1822. To be happy as a clam is from 1833, but the earliest uses do not elaborate on the notion behind it, unless it be self-containment.
clam-shell (n.) Look up clam-shell at Dictionary.com
c. 1500; see clam (n.) + shell (n.). As "hinged iron box or bucket used in dredging," from 1877.
clambake (n.) Look up clambake at Dictionary.com
1835, American English, from clam (n.) + bake (n.). By 1937 in jazz slang transferred to "an enjoyable time generally," especially "jam session."
clamber (v.) Look up clamber at Dictionary.com
"to climb with difficulty using hands and feet," late 14c., possibly frequentative of Middle English climben "to climb" (preterit clamb), or akin to Old Norse klembra "to hook (oneself) on." Related: Clambered; clambering.
clamjamphry (n.) Look up clamjamphry at Dictionary.com
contemptuous word for "a collection of persons, mob," 1816, of unknown origin; first in Scott, so perhaps there's a suggestion of clan in it.
clammy (adj.) Look up clammy at Dictionary.com
"soft and sticky," late 14c., probably from Middle English clam "viscous, sticky, muddy" (mid-14c.), from Old English clæm "mud, sticky clay," from Proto-Germanic *klaimaz "clay" (source also of Flemish klammig, Low German klamig "sticky, damp," Old English clæman "to smear, plaster;" source also of clay). With -y (2). Related: Clammily; clamminess.
clamor (v.) Look up clamor at Dictionary.com
late 14c., from clamor (n.). Related: Clamored; clamoring.
clamor (n.) Look up clamor at Dictionary.com
late 14c., from Old French clamor "call, cry, appeal, outcry" (12c., Modern French clameur), from Latin clamor "a shout, a loud call" (either friendly or hostile), from clamare "to cry out" (from PIE root *kele- (2) "to shout").
clamorous (adj.) Look up clamorous at Dictionary.com
c. 1400, from Middle French clamoreux or directly from Medieval Latin clamorosus, from Latin clamor "a shout" (see clamor (n.)). Related: Clamorously; clamorousness.
clamour Look up clamour at Dictionary.com
chiefly British English spelling of clamor (q.v.); for spelling, see -or. Related: Clamoured; clamouring; clamourous.
clamp (v.) Look up clamp at Dictionary.com
"to fasten with a clamp," 1670s, from clamp (n.). Related: Clamped; clamping.
clamp (n.) Look up clamp at Dictionary.com
device for fastening, c. 1300, probably from clamb, perhaps originally past tense of climb (v.), or from Middle Dutch clampe (Dutch klamp), from Proto-Germanic *klam-b- "clamp, cleat;" cognate with Middle Low German klampe "clasp, hook," Old High German klampfer "clip, clamp;" also probably related to Middle Dutch klamme "a clamp, hook, grapple," Danish klamme "a clamp, cramp," Old English clamm "a tie, fetter," perhaps from the same root as Latin glomus "ball-shaped mass" (see glebe); also compare clam (n.).
clamp-down (n.) Look up clamp-down at Dictionary.com
also clampdown, 1940 in the figurative sense, from verbal phrase clamp down "use pressure to keep down" (1924). The verbal phrase in the figurative sense is recorded from 1941. See clamp (v.) + down (adv.).
clan (n.) Look up clan at Dictionary.com
early 15c., from Gaelic clann "family, stock, offspring," akin to Old Irish cland "offspring, tribe," both from Latin planta "offshoot" (see plant (n.)). The Goidelic branch of Celtic (including Gaelic) had no initial p-, so it substituted k- or c- for Latin p-. The same Latin word in (non-Goidelic) Middle Welsh became plant "children."
clandestine (adj.) Look up clandestine at Dictionary.com
1560s, from Latin clandestinus "secret, hidden," from clam "secretly," from adverbial derivative of base of celare "to hide" (from PIE root *kel- (1) "to cover, conceal, save"), perhaps on model of intestinus "internal." Related: Clandestinely. As a noun form, there is awkward clandestinity (clandestineness apparently being a dictionary word).
clang (v.) Look up clang at Dictionary.com
1570s, echoic (originally of trumpets and birds), akin to or from Latin clangere "resound, ring," and Greek klange "sharp sound," from PIE *klang-, nasalized form of root *kleg- "to cry, sound." Related: Clanged; clanging.
clang (n.) Look up clang at Dictionary.com
1590s, from clang (v.).
clangor (n.) Look up clangor at Dictionary.com
1590s, from Latin clangor "sound of trumpets (Virgil), birds (Ovid), etc.," from clangere "to clang," echoic (compare clang).
clangorous (adj.) Look up clangorous at Dictionary.com
1712, from Medieval Latin clangorosus, from Latin clangor, or else from clangor + -ous. Related: Clangorously; clangorousness.
clank (v.) Look up clank at Dictionary.com
1610s, perhaps echoic, perhaps a blend of clang (v.) and clink (v.), perhaps from a Low German source (compare Middle Dutch clank, Dutch klank, Old High German klanc, Middle Low German klank, German Klang).
clank (n.) Look up clank at Dictionary.com
1650s, from clank (v.). Reduplicated form clankety-clank attested from 1895.
clannish (adj.) Look up clannish at Dictionary.com
"disposed to adhere closely to one another," 1747, from clan + -ish. Related: Clannishly; clannishness.
clansman (n.) Look up clansman at Dictionary.com
1810, "member of a clan," from genitive of clan + man (n.).
clap (n.1) Look up clap at Dictionary.com
"loud noise," c. 1200, from clap (v.). Of thunder, late 14c. Meaning "sudden blow" is from c. 1400; meaning "noise made by slapping the palms of the hands together" is from 1590s.
clap (v.) Look up clap at Dictionary.com
Old English clæppan "to throb, beat," common Germanic, echoic (cognate with Old Frisian klapa "to beat," Old Norse klappa, Old High German klaphon, German klappen, Old Saxon klapunga). Meaning "to strike or knock" is from c. 1300. Meaning "to make a sharp noise" is late 14c. Of hands, to beat them together to get attention or express joy, from late 14c. To clap (someone) on the back is from 1520s. Related: Clapped; clapping.
clap (n.2) Look up clap at Dictionary.com
"gonorrhea," 1580s, of unknown origin, perhaps from Middle English clapper "rabbit-hole," from Old French clapoire (Modern French clapier), originally "rabbit burrow" (of uncertain origin), but given a slang extension to "brothel" and also the name of a disease of some sort. In English originally also a verb, "to infect with clap." Related: Clap-doctor.