Online Etymology Dictionary

cameo (n.): early 15c., kaadmaheu, camew, chamehieux and many other spellings (from early 13c. in Anglo-Latin), "carved precious stone with two layers of colors," from Old French camaieu and directly from Medieval Latin cammaeus, which is of unknown origin, perhaps ultimately from Arabic qamaa'il "flower buds," or Persian chumahan "agate." Transferred sense of "small character or part that stands out from other minor parts" in a play, etc., is from 1928, from earlier meaning "short literary sketch or portrait" (1851), a transferred sense from cameo silhouettes.
camera (n.): 1708, "vaulted building," from Latin camera "vaulted room" (source of Italian camera, Spanish camara, French chambre), from Greek kamara "vaulted chamber."

The word also was used early 18c. as a short form of Modern Latin camera obscura "dark chamber" (a black box with a lens that could project images of external objects), contrasted with camera lucida (Latin for "light chamber"), which uses prisms to produce on paper beneath the instrument an image, which can be traced. It became the word for "picture-taking device" when modern photography began, c. 1840 (extended to television filming devices 1928). Camera-shy is attested from 1890. Old Church Slavonic komora, Lithuanian kamara, Old Irish camra all are borrowings from Latin.
camera obscura (n.): 1725, "a darkened room;" c. 1730, "a device for project pictures;" see camera.
camerlengo (n.): "papal chamberlain," from Italian camerlingo "chamberlain" (see chamberlain).
Cameron: Highland clan name, from Gaelic camshron "wry or hooked nose."
Camilla: fem. proper name, from Latin, fem. of Camillus, cognomen of several members of the gens Furia, from camillus "noble youth attending at sacrifices," perhaps from Etruscan.
camisole (n.): 1816, from French camisole (16c.), from Provençal camisola "mantle," diminutive of camisa "shirt," from Late Latin camisia "shirt, nightgown" (see chemise).
camomile (n.): mid-13c., from Old French camemile, from Late Latin camomilla, from Latin chamomilla, from Greek chamaimelon, literally "earth apple," from chamai "on the ground" (also "dwarf;" see chameleon) + melon "apple" (see malic). So called for its scent. Old English had it as camemalon.
camouflage: 1917, noun, verb, and adjective, from French camoufler, Parisian slang, "to disguise," from Italian camuffare "to disguise," which is of uncertain origin, perhaps a contraction of capo muffare "to muffle the head." Probably altered by influence of French camouflet "puff of smoke," on the notion of "blow smoke in someone's face." The British navy in World War I called it dazzle-painting.
Since the war started the POPULAR SCIENCE MONTHLY has published photographs of big British and French field pieces covered with shrubbery, railway trains "painted out" of the landscape, and all kinds of devices to hide the guns, trains, and the roads from the eyes of enemy aircraft.

Until recently there was no one word in any language to explain this war trick. Sometimes a whole paragraph was required to explain this military practice. Hereafter one word, a French word, will save all this needless writing and reading. Camouflage is the new word, and it means "fooling the enemy." ["Popular Science Monthly," August 1917]
camp (adj.): "tasteless," 1909, homosexual slang, of uncertain origin, perhaps from mid-17c. French camper "to portray, pose" (as in se camper "put oneself in a bold, provocative pose"); popularized 1964 by Susan Sontag's essay "Notes on Camp." Campy is attested from 1959.
camp (n.): "place where an army lodges temporarily," 1520s, from French camp, from Italian campo, from Latin campus "open field, level space" (also source of French champ; see campus), especially "open space for military exercise."

A later reborrowing of the Latin word, which had been taken up in early West Germanic as *kampo-z and appeared originally in Old English as camp "contest, battle, fight, war." This was obsolete by mid-15c. Transferred to non-military senses 1550s. Meaning "body of adherents of a doctrine or cause" is 1871. Camp-follower first attested 1810. Camp-meeting is from 1809, originally usually in reference to Methodists. Camp-fever (1758) is any epidemic fever incident to life in a camp, especially typhus or typhoid.
camp (v.): "to encamp," 1540s, from camp (n.). Related: Camped; camping. Camping out is attested from 1834, American English.
Camp David: U.S. presidential retreat near Thurmont, Maryland, built 1939 as Hi-Catoctin, in reference to the name of the mountains around it; called Shangri-La by F.D. Roosevelt, after the mythical hard-to-get-to land in the novel "Lost Horizon;" named Camp David by Eisenhower in 1953 for his grandson, born 1947. The Camp David Accords were signed there Sept. 17, 1978.
campagne (n.): obsolete form of campaign.
campaign (n.): 1640s, "operation of an army in the field," during a single season, in a particular region, or in a definite enterprise; from French campagne "campaign," literally "open country," from Old French champagne "countryside, open country" (suited to military maneuvers), from Late Latin campania "level country" (source of Italian campagna, Spanish campaña, Portuguese campanha), from Latin campus "a field" (see campus). Old armies spent winters in quarters and took to the "open field" to seek battle in summer. Extension of meaning to "political activity before an election, marked by organized action in influencing the voters" [DAE] is American English, 1809.
campaign (v.): 1701, from campaign (n.). Political sense is from 1801. Related: Campaigned; campaigning.
campanile (n.): 1630s, from Italian, from campana "bell," from Late Latin campana, originally "metal vessel made in Campania," region around Naples.
Campbell: family name, from Gaelic caimbeul "wry or crooked mouth," from cam "crooked, deformed, one-eyed, cross-eyed." Also in surname Cameron, from Gaelic camshron "wry or hooked nose" (in the Highland clan; the Lowland name is for a locality in Fife). The Campbell Soup Company was started in 1869 by Joseph A. Campbell; Warhol began painting their cans in 1962.
Campbellite (n.): 1830, follower of Alexander Campbell, preacher from Virginia, U.S.A. They called themselves Disciples.
camper (n.): 1630s, "soldier," agent noun from camp (v.). Meaning "attendee at a camp meeting" is from 1806; meaning "one who sleeps in temporary quarters outdoors" is from 1856; that of "motor vehicle with sleeping quarters" is from 1960. Extended use of happy camper is from c. 1987.
campfire (n.): also camp-fire, 1835, from camp (n.) + fire (n.).
camphor (n.): substance extensively used in medicine, early 14c., caumfre, from Old French camphre, from Medieval Latin camfora, from Arabic kafur, perhaps via Sanskrit karpuram, from Malay kapur "camphor tree." Related: Camphorated.
campus (n.): "college grounds," 1774, from Latin campus "a field," probably properly "an expanse surrounded" (by woods, higher ground, etc.), from PIE *kampos "a corner, cove," from root *kamp- "to bend" (source also of Lithuanian kampus "corner," Polish kępa "cluster of trees or brush"). First used in college sense at Princeton.
can (v.1): Old English 1st & 3rd person singular present indicative of cunnan "know, have power to, be able," (also "to have carnal knowledge"), from Proto-Germanic *kunnan "to be mentally able, to have learned" (source also of Old Norse kenna "to know, make known," Old Frisian kanna "to recognize, admit," German kennen "to know," Gothic kannjan "to make known"), from PIE root *gno- (see know).

Absorbing the third sense of "to know," that of "to know how to do something" (in addition to "to know as a fact" and "to be acquainted with" something or someone). An Old English preterite-present verb, its original past participle, couth, survived only in its negation (see uncouth), but see also could. The present participle has spun off as cunning.
can (n.): Old English canne "a cup, container," from Proto-Germanic *kanna (source also of Old Saxon, Old Norse, Swedish kanna, Middle Dutch kanne, Dutch kan, Old High German channa, German Kanne). Probably an early borrowing from Late Latin canna "container, vessel," from Latin canna "reed," also "reed pipe, small boat;" but the sense evolution is difficult.

Modern "air-tight vessel of tinned iron" is from 1867 (can-opener is from 1877). Slang meaning "toilet" is c. 1900, said to be a shortening of piss-can. Meaning "buttocks" is from c. 1910.
can (v.2): "to put up in cans," 1860, from can (n.1). Sense of "to fire an employee" is from 1905. Related: Canned; canning.
can't (v.): 1706, contraction of cannot.
can-do (adj.): by 1952, from expression can do "it is possible," literally "(I or we) can do (it)," 1903, perhaps based on earlier no can do (see no).
Canada: 1560s (implied in Canadian), said to be a Latinized form of a word for "village" in an Iroquoian language of the St. Lawrence valley that had gone extinct by 1600. Most still-spoken Iroquoian languages have a similar word (such as Mohawk kana:ta "town"). Canada goose is attested from 1772.
Canadian: 1560s; see Canada.
Canadianism (n.): 1875, from Canadian + -ism.
canaille (n.): "rabble," from French canaille (16c.), from Italian canaglia, literally "a pack of dogs," from cane "dog" (see canine).
canal (n.): early 15c., from French canal, chanel "water channel, tube, pipe, gutter" (12c.), from Latin canalis "water pipe, groove, channel," noun use of adjective from canna "reed" (see cane (n.)). Originally in English "a pipe for liquid," its sense transferred by 1670s to "artificial waterway."
canard (n.): before 1850, from French canard "a hoax," literally "a duck" (from Old French quanart, probably echoic of a duck's quack); said by Littré to be from the phrase vendre un canard à moitié "to half-sell a duck," thus, from some long-forgotten joke, "to cheat."
canary (n.): type of small songbird, 1650s (short for Canary-bird, 1570s), from French canarie, from Spanish canario "canary bird," literally "of the Canary Islands," from Latin Insula Canaria "Canary Island," largest of the Fortunate Isles, literally "island of dogs" (canis, genitive canarius; see canine (n.)), so called because large dogs lived there. The name was extended to the whole island group (Canariæ Insulæ) by the time of Arnobius (c.300). As a type of wine (from the Canary Islands) from 1580s.
canasta (n.): 1948, Uruguayan card game played with two decks and four jokers, popular c. 1945-1965; from Spanish, literally "basket," from Latin canistrum (see cannister); perhaps in reference to the "packs" of cards used.
Canberra: capital of Australia, 1826, from Aborigine nganbirra "meeting place."
cancan (n.): also can-can, 1848, from French, possibly from can, a French children's word for "duck" (see canard), via some notion of "waddling" too obscure or obscene to attempt to disentangle here. Or perhaps from French cancan (16c.) "noise, disturbance," echoic of quacking.
cancel (v.): late 14c., "cross out with lines," from Anglo-French canceler, from Latin cancellare "to make resemble a lattice," which in Late Latin took on a sense "cross out something written" by marking it with crossed lines, from cancelli, plural of cancellus "lattice, grating," diminutive of cancer "crossed bars, lattice," a variant of carcer "prison" (see incarceration). Figurative use, "to nullify an obligation" is from mid-15c. Related: Canceled (also cancelled); cancelling.
cancellation (n.): also cancelation, 1530s, from Latin cancellationem (nominative cancellatio), noun of action from past participle stem of cancellare "to cancel" (see cancel). Of reservations for conveyances, hotels, etc., from 1953.
cancer (n.): Old English cancer "spreading sore, cancer" (also canceradl), from Latin cancer "a crab," later, "malignant tumor," from Greek karkinos, which, like the Modern English word, has three meanings: crab, tumor, and the zodiac constellation (late Old English), from PIE root *qarq- "to be hard" (like the shell of a crab); source also of Sanskrit karkatah "crab," karkarah "hard;" and perhaps cognate with PIE root *qar-tu- "hard, strong," source of English hard.

Greek physicians Hippocrates and Galen, among others, noted similarity of crabs to some tumors with swollen veins. Meaning "person born under the zodiac sign of Cancer" is from 1894. The sun being in Cancer at the summer solstice, the constellation had association in Latin writers with the south and with summer heat. Cancer stick "cigarette" is from 1959.
cancerous (adj.): 1560s, from cancer + -ous.
candela (n.): unit of luminous intensity, 1950, from Latin candela (see candle).
candelabrum (n.): 1811, from Latin candelabrum, which meant "candlestick," from candela (see candle). Old English had candeltreow "candle-tree" in same sense. The word was borrowed earlier (late 14c.) from Old French as chaundelabre with the Latin sense. Candelabra is the Latin plural.
candescent (adj.): 1824, from Latin candescentem (nominative candescens), present participle of candescere "to become white, begin to gleam," inchoative of candere "to shine, to glow" (see candle).
candid (adj.): 1620s, "white," from Latin candidum "white; pure; sincere, honest, upright," from candere "to shine," from PIE root *kand- "to glow, to shine" (see candle). In English, metaphoric extension to "frank" first recorded 1670s (compare French candide "open, frank, ingenuous, sincere"). Of photography, 1929. Related: Candidly; candidness.
candidacy (n.): 1822; see candidate + -cy.
candidate (n.): c. 1600s, from Latin candidatus "one aspiring to office," originally "white-robed," past participle of candidare "to make white or bright," from candidus (see candid). Office-seekers in ancient Rome wore white togas.
candied (adj.): c. 1600, past participle adjective from candy (v.).
candle (n.): Old English candel "lamp, lantern, candle," an early ecclesiastical borrowing from Latin candela "a light, torch, candle made of tallow or wax," from candere "to shine," from PIE root *kand- "to glow, to shine, to shoot out light" (source also of Sanskrit cand- "to give light, shine," candra- "shining, glowing, moon;" Greek kandaros "coal;" Welsh cann "white;" Middle Irish condud "fuel").

Candles were unknown in ancient Greece (where oil lamps sufficed), but common from early times among Romans and Etruscans. Candles on birthday cakes seems to have been originally a German custom. To hold a candle to originally meant "to help in a subordinate capacity," from the notion of an assistant or apprentice holding a candle for light while the master works (compare Old English taporberend "acolyte"). To burn the candle at both ends is recorded from 1730.