Online Etymology Dictionary

cubism (n.): 1911, from French cubisme, from cube (see cube (n.)), said to have been coined by French art critic Louis Vauxcelles at the 1908 Salon des Indépendants in reference to a work by Georges Braque. Related: Cubist.
cubit (n.): ancient unit of measure based on the forearm from elbow to fingertip, usually from 18 to 22 inches, early 14c., from Latin cubitum "the elbow," from PIE *keu(b)- "to bend." Such a measure, known by a word meaning "forearm" or the like, was known to many peoples (e.g. Greek pekhys, Hebrew ammah, English ell).
cuboid (adj.): "cube-like," 1829, a modern coinage; see cube (n.) + -oid.
cucking stool (n.): early 13c., from cuck "to void excrement," from Old Norse kuka "feces" (the chair was sometimes in the form of a close-stool). Also known as trebucket and castigatory, it was used on disorderly women and fraudulent tradesmen, either in the form of public exposure to ridicule or for ducking in a pond.
cuckold (n.): mid-13c., kukewald, from Old French cucuault, from cocu (see cuckoo) + pejorative suffix -ault, of Germanic origin. So called from the female bird's alleged habit of changing mates, or her authentic habit of leaving eggs in another bird's nest.

In Modern French the identity is more obvious: Coucou for the bird and cocu for the betrayed husband. German Hahnrei (13c.), from Low German, is of obscure origin. The second element seems to be connected to words for "ardent," and suggests perhaps "sexually aggressive hen," with transferal to humans, but Kluge suggests rather a connection to words for "capon" and "castrated." Related: Cuckoldry.
cuckold (v.): 1580s, from cuckold (n.). Related: Cuckolded; cuckolding.
cuckoo (n.): mid-13c., from Old French cocu "cuckoo," also "cuckold," echoic of the male bird's mating cry (cf. Greek kokkyx, Latin cuculus, Middle Irish cuach, Sanskrit kokilas). Slang sense of "crazy" (adj.) is American English, 1918, but noun meaning "stupid person" is first recorded 1580s, perhaps from the bird's unvarying, oft-repeated call. The Old English name was geac, cognate with Old Norse gaukr, source of Scottish and northern English gowk. The Germanic words presumably originally were echoic, too, but had drifted in form. Cuckoo clock is from 1789.
cucumber (n.): late 14c., from Old French cocombre (13c., Modern French concombre), from Latin cucumerem (nominative cucumis), perhaps from a pre-Italic Mediterranean language. The Latin word also is the source of Italian cocomero, Spanish cohombro, Portuguese cogombro. Replaced Old English eorþæppla (plural), literally "earth-apples."

Cowcumber was common form 17c.-18c., and that pronunciation lingered into 19c. Planted as a garden vegetable by 1609 by Jamestown colonists. Phrase cool as a cucumber (c.1732) embodies ancient folk knowledge confirmed by science in 1970: inside of a field cucumber on a warm day is 20 degrees cooler than the air temperature.
cud (n.): Old English cudu "cud," earlier cwudu, common Germanic (cf. Old Norse kvaða "resin," Old High German quiti "glue," German Kitt "putty"); perhaps from PIE root *gwet- "resin, gum."
cuddle (v.): early 16c. (implied in cudlyng), perhaps a variant of obsolete cull, coll "to embrace" (see collar (n.)); or perhaps from Middle English *couthelen, from couth "known," hence "comfortable with." It has a spotty early history and seems to have been a nursery word at first. Related: Cuddled; cuddling.
cuddly (adj.): 1863, from cuddle + -y (2).
cudgel (n.): Old English cycgel "club with rounded head;" perhaps from PIE root *geu- "to curve, bend."
cudgel (v.): "to beat with a cudgel," 1590s, from cudgel (n.). Related: Cudgeled; cudgeling.
cue (v.): 1928, from cue (n.1). Related: Cued, cueing.
cue (n.1): "stage direction," 1550s, from Q, which was used 16c., 17c. in stage plays to indicate actors' entrances, probably as an abbreviation of Latin quando "when" (see quandary) or a similar Latin adverb. Shakespeare has it as both Q and cue.
cue (n.2): "billiard stick," 1749, variant of queue (n.). Cue ball first recorded 1881.
cuff (v.1): "to put a cuff on," 1690s, from cuff (n.). Related: Cuffed; cuffing.
cuff (n.): "bottom of a sleeve," mid-14c., cuffe "hand covering, mitten, glove," perhaps somehow from Medieval Latin cuffia "head covering," of uncertain origin. Sense of "band around the sleeve" is first attested 1520s; sense of "hem of trousers" is 1911. Off the cuff "extemporaneously" is 1938 American English colloquial, suggesting an actor or speaker reading from notes jotted on his shirt sleeves rather than learned lines. Cuff links is from 1897.
cuff (v.2): "hit," 1520s, of unknown origin, perhaps from Swedish kuffa "to thrust, push." Related: Cuffed; cuffing. As a noun from 1560s.
cui bono: a Latin phrase from Cicero. It means "to whom for a benefit," or "who profits by it?" not "to what good purpose?" as is often erroneously claimed. From cui "to? for whom?," an old form preserved here in the dative form of the interrogative pronoun quis "who?" (see who) + bono "good" (see bene-).
cuirass (n.): "armor for the chest and back," mid-15c., from Middle French cuirasse (15c.), from Late Latin coriacea vestis "garment of leather," from Latin corium "leather, hide" (see corium). Cognate with Italian corazza, Spanish coraza, Portuguese couraça.
cuisine (n.): 1786, from French cuisine "style of cooking," originally "kitchen, cooking, cooked food" (12c.), from Late Latin cocina, earlier coquina "kitchen," from Latin coquere "to cook" (see cook (n.)).
cul-de-sac (n.): 1738, as an anatomical term, from French cul-de-sac, literally "bottom of a sack," from Latin culus "bottom" (for second element, see sack (n.1)). Application to streets and alleys is from 1800.
culdee (n.): mid-12c., from Old Irish céle de "anchorite," from cele "associate, companion," sometimes "servant" (cf. ceilidh) + de "of God." Perhaps an attempt to translate Servus Dei or some other Latin term for "religious hermit."
culinary (adj.): 1630s, "of the kitchen," from Latin culinarius "pertaining to the kitchen," from culina "kitchen, food" (see kiln). Meaning "of cookery" is from 1650s.
cull (v.): c.1200, originally "put through a strainer," from Old French coillir (12c., Modern French cueillir) "collect, gather, pluck, select," from Latin colligere "gather together, collect," originally "choose, select" (see collect). Related: Culled; culling. As a noun, from 1610s.
cull (n.): "dupe, saphead," rogues' slang from late 16c., perhaps a shortening of cullion "base fellow," originally "testicle" (from French couillon, from Old French coillon "testicle; worthless fellow, dolt," from Latin coleus, literally "strainer bag;" see cojones), though another theory traces it to Romany (Gypsy) chulai "man." Also sometimes cully, though some authorities assert cully was the canting term for "dupe" and cull was generic "man, fellow," without implication of gullibility. Cf. also gullible.
cullen: in some uses it represents an Anglicization of Cologne, the city in Germany. As a surname it can be this or from Cullen, Banffshire.
culminate (v.): 1640s, from Late Latin culminatus past participle of culminare "to top, to crown," from Latin culmen (genitive culminis) "top, peak, summit, roof, gable," also used figuratively, contraction of columen (see column). Related: Culminated; culminating.
culmination (n.): 1630s, from French culmination, noun of action from past participle stem of Late Latin culminare (see culminate). Originally a term in astronomy/astrology; figurative use is from 1650s.
culottes (n.): "a divided skirt," 1911, from French culotte "breeches" (16c.), a diminutive of cul "bottom, backside, anus," from Latin culus "bottom, fundament." Earlier, in the singular cullote, it was used to mean "knee-breeches" (1842). Por le cul bieu "By God's arse" was an Old French oath.
culpability (n.): 1670s, from Late Latin culpabilitas "guilt, culpability," from Latin culpabilis (see culpable).
culpable (adj.): late 13c., coupable, from Old French coupable (12c., Modern French coupable), from Latin culpabilis "worthy of blame," from culpare "to blame," from culpa "crime, fault, blame, guilt, error." English (and for a time French) restored the first Latin -l- in later Middle Ages.
culprit (n.): 1670s, from Anglo-French cul prit, contraction of Culpable: prest (d'averrer nostre bille) "guilty, ready (to prove our case)," words used by prosecutor in opening a trial. It seems the abbreviation cul. prit was mistaken in English for an address to the defendant.
cult (n.): 1610s, "worship," also "a particular form of worship," from French culte (17c.), from Latin cultus "care, labor; cultivation, culture; worship, reverence," originally "tended, cultivated," past participle of colere "to till" (see colony). Rare after 17c.; revived mid-19c. with reference to ancient or primitive rituals. Meaning "devotion to a person or thing" is from 1829.
Cult. An organized group of people, religious or not, with whom you disagree. [Rawson]
cultivar (n.): 1923, from culti(vated) var(iety), coined by U.S. horticulturalist Liberty Hyde Bailey (1858-1954) in "Gentes Herbarum."
cultivate (v.): early 17c., from Medieval Latin cultivatus, past participle of cultivare, from Late Latin cultivus "tilled," from Latin cultus (see cult). Figurative sense of "improve by training or education" is from 1680s. Related: Cultivable; cultivated; cultivating.
cultivation (n.): c.1700, of knowledge, etc., a figurative use, from French cultivation (16c.), noun of action from cultiver, from Latin cultivare "to till" (see cultivate). Meaning "raising of a plant or crop" is from 1719; literal sense of "tilling of the land" is from 1725.
cultivator (n.): 1660s, noun of action (in Latin form) from cultivate. As the name of an agricultural tool, from 1759.
cultural (adj.): 1868, in reference to the raising of plants or animals, from Latin cultura "tillage" (see culture) + -al (1). In reference to the cultivation of the mind, from 1875; hence, "relating to civilization or a civilization." A fertile starter-word among anthropologists and sociologists: e.g. cultural diffusion, in use by 1912; cultural diversity by 1935; cultural imperialism by 1937; cultural pluralism by 1932; cultural relativism by 1948.
Cultural Revolution: 1966, from Chinese, translation of Wuchan Jieji Wenhua Da Geming "Proletarian Cultural Great Revolution."
culturalization (n.): by 1929; see cultural + -ization.
culturally (adv.): 1889, from cultural + -ly (2).
culture (n.): mid-15c., "the tilling of land," from Middle French culture and directly from Latin cultura "a cultivating, agriculture," figuratively "care, culture, an honoring," from past participle stem of colere "tend, guard, cultivate, till" (see cult). The figurative sense of "cultivation through education" is first attested c.1500. Meaning "the intellectual side of civilization" is from 1805; that of "collective customs and achievements of a people" is from 1867.
For without culture or holiness, which are always the gift of a very few, a man may renounce wealth or any other external thing, but he cannot renounce hatred, envy, jealousy, revenge. Culture is the sanctity of the intellect. [William Butler Yeats]
Slang culture vulture is from 1947. Culture shock first recorded 1940.
culvert (n.): 1773, origin unknown, perhaps, as Weekley suggests, the name of a long-forgotten engineer or bridge-builder.
cum: verb and noun, by 1973, apparently a variant of the sexual sense of come that originated in pornographic writing, perhaps first in the noun sense. This "experience sexual orgasm" slang meaning of come (perhaps originally come off) is attested from 1650, in "Walking In A Meadowe Greene," in a folio of "loose songs" collected by Bishop Percy.
They lay soe close together, they made me much to wonder;
I knew not which was wether, until I saw her under.
Then off he came, and blusht for shame soe soon that he had endit;
Yet still she lies, and to him cryes, "one more and none can mend it."
As a noun meaning "semen or other product of orgasm" it is on record from the 1920s. The sexual cum seems to have no connection with Latin cum, the preposition meaning "with, together with," which is occasionally used in English in local names of combined parishes or benifices (e.g. Chorlton-cum-Hardy), in popular Latin phrases (e.g. cum laude), or as a combining word to indicate a dual nature or function (e.g. slumber party-cum-bloodbath).
cum laude: 1872, originally at Harvard, from Medieval Latin, literally "with praise," from Latin cum "with" + laude, ablative of laus (genitive laudis) "praise" (see laud). Probably from earlier use (in Latin) at Heidelberg and other German universities.
Cumaean (adj.): 1731, from Latin Cumae (Greek Kyme), ancient city on the Italian coast near Naples, founded by Greeks 8c. B.C.E.; especially famous for the Sybil there, mentioned by Virgil.
cumber (v.): c.1300, "to overthrow, destroy; to be overwhelmed; to harass," apparently from French, but Old French combrer "to seize hold of, lay hands on, grab, snatch, take by force, rape," has not quite the same sense. Perhaps a shortened formation from a verb akin to Middle English acombren "obstructing progress," from Old French encombrer, from combre "obstruction, barrier," from Vulgar Latin *comboros "that which is carried together," perhaps from a Gaulish word.

The likely roots are PIE *kom (see com-) + *bher- (1) "to bear" (see infer). Weakened sense of "to hamper, to obstruct or weigh down" is late 14c. Related: Cumbered; cumbering.
Cumberland: Old English Cumbra land (945) "region of the Cymry" (see Cymric).