Online Etymology Dictionary

clot (n.): Old English clott "a round mass, lump," akin to Dutch kloot "ball," Danish klods "a block, lump," German Klotz "lump, block;" probably related to cleat and clod.
clot (v.): early 15c., from clot (n.). Of fluids from 1590s. Related: Clotted; clotting.
cloth (n.): Old English claþ "a cloth, sail, cloth covering, woven or felted material to wrap around one," hence, also, "garment," from Proto-Germanic *kalithaz (source also of Old Frisian klath "cloth," Middle Dutch cleet, Dutch kleed "garment, dress," Middle High German kleit, German Kleid "garment"), of obscure origin. As an adjective from 1590s. The cloth "the clerical profession" is from 17c. in reference to characteristic dress.
clothe (v.): Old English claðian, from claþ (see cloth). Related: Clothed, clothing. Other Old English words for this were scrydan and gewædian.
clothes (n.): Old English claðas "cloths, clothes," originally plural of clað "cloth" (see cloth), which, in 19c., after the sense of "article of clothing" had mostly faded from it, acquired a new plural form, cloths, to distinguish it from this word.
clothes-horse (n.): also clothes horse, "upright wooden frame for hanging clothes to dry," 1788, from clothes + horse (n.). Figurative sense of "person whose sole function seems to be to show off clothes" is 1850.
clothes-line (n.): also clothesline, 1830, from clothes + line (n.). As a kind of high tackle in U.S. football (the effect is similar to running into a taut clothesline) attested by 1970; as a verb in this sense by 1959.
clothes-pin (n.): also clothespin, by 1834, American English, from clothes + pin (n.). Clothes-peg in the same sense attested from 1812.
clothier (n.): mid-14c., clother; late 15c., clothyer (late 13c. as a surname) Middle English agent noun from cloth; also see -ier, which is unetymological in this word and probably acquired by bad influence.
Clothilde: fem. proper name, via French, from German Klothilde, literally "famous in battle," from Old High German *klod "famous" (related to Old English hlud; see loud (adj.)) + hild "battle" (see Hilda).
clothing (n.): c. 1200, "action of dressing in clothes," verbal noun from clothe. From late 13c. as "clothes collectively;" 1590s as an adjective.
Clotho: one of the three Fates, from Latin Clotho, from Greek Klotho, literally "the spinner," from klothein "to spin." The three Fates together sometimes were called Klothes "the spinners."
cloture (n.): 1871, the French word for "closure, the action of closing," applied to debates in the French Assembly ("action of closing (debate) by will of a majority"), then to the House of Commons and U.S. Congress, from French clôture, from Old French closture (see closure). It was especially used in English by those opposed to the tactic.
In foreign countries the Clôture has been used notoriously to barricade up a majority against the "pestilent" criticism of a minority, and in this country every "whip" and force is employed by the majority to re-assert its continued supremacy and to keep its ranks intact whenever attacked. How this one-sided struggle to maintain solidarity can be construed into "good for all" is inexplicable in the sense uttered. ["The clôture and the Recent Debate, a Letter to Sir J. Lubbock," London, 1882]
cloud (n.): Old English clud "mass of rock, hill," related to clod. Metaphoric extension to "raincloud, mass of evaporated water in the sky" is attested by c. 1200 based on similarity of cumulus clouds and rock masses. The usual Old English word for "cloud" was weolcan. In Middle English, skie also originally meant "cloud."

The four fundamental types of cloud classification (cirrus, cumulus, stratus, nimbus) were proposed by British amateur meteorologist Luke Howard (1772-1864) in 1802. Figuratively, as something that casts a shadow, from early 15c.; hence under a cloud (c. 1500). In the clouds "removed from earthly things; obscure, fanciful, unreal" is from 1640s. Cloud-compeller translates (poetically) Greek nephelegereta, a Homeric epithet of Zeus.
cloud (v.): early 15c., "overspread with clouds, cover, darken," from cloud (n.). From 1510s as "to render dim or obscure;" 1590s as "to overspread with gloom." Intransitive sense of "become cloudy" is from 1560s. Related: Clouded; clouding.
Cloud Cuckoo Land: Imaginary city built in air, translating Aristophanes' Nephelokokkygia in "The Birds" (414 B.C.E.).
cloud nine (n.): by 1950, sometimes also cloud seven (1956, perhaps by confusion with seventh heaven), American English, of uncertain origin or significance. Some connect the phrase with the 1895 International Cloud-Atlas (Hildebrandsson, Riggenbach and Teisserenc de Bort), long the basic source for cloud shapes, in which, of the ten cloud types, cloud No. 9, cumulonimbus, was the biggest, puffiest, most comfortable-looking. Shipley suggests the sense in this and other expressions might be because, "As the largest one-figure integer, nine is sometimes used for emphasis." The phrase might appear in the 1935 aviation-based play "Ceiling Zero" by Frank Wilbur Wead.
cloudburst (n.): also cloud-burst, 1817, American English, from cloud (n.) + burst (n.). Parallels German Wolkenbruch.
cloudless (adj.): 1590s, from cloud (n.) + -less.
cloudlet (n.): 1788, from cloud (n.) + diminutive suffix -let.
cloudy (adj.): Old English cludig "rocky, hilly, full of cliffs;" see cloud (n.). Meaning "of the nature of clouds" is recorded from c. 1300; meaning "full of clouds" is late 14c.; that of "not clear" is from 1580s. Figurative sense of "gloomy" is late 14c. Related: Cloudiness; cloudily.
clough (n.): "ravine with a river," Old English cloh (in place names), of uncertain origin.
clout (n.): Old English clut "lump of something," also "patch of cloth put over a hole to mend it," from Proto-Germanic *klutaz (source also of Old Norse klute "kerchief," Danish klud "rag, tatter," Frisian klut "lump," Dutch kluit "clod, lump"); perhaps related to clot (v.).

In later use "a handkerchief," also "a woman's sanitary napkin." Sense of "a blow" is from c. 1400 early 14c., from the verb. Sense of "personal influence" is 1958, on the notion of "punch, force."
clout (v.): "to beat, strike," early 14c., from clout (n.), perhaps on the notion of hitting someone with a lump of something, or from the "patch of cloth" sense of that word (compare clout (v.) "to patch, mend," mid-14c.). Related: Clouted; clouting.
clove (n.1): dried flowerbud of a certain tropical tree, used as a spice, late 15c., earlier clowes (14c.), from Anglo-French clowes de gilofre (c. 1200), Old French clou de girofle "nail of gillyflower," so called from its shape, from Latin clavus "a nail" (see slot (n.2)). For second element, see gillyflower. The two cloves were much confused in Middle English. The clove pink is so called from the scent of the flowers.
clove (n.2): "slice of garlic," Old English clufu "clove (of garlic), bulb, tuber," from Proto-Germanic *klubo "cleft, thing cloven," from PIE *gleubh- "to tear apart, cleave" (see cleave (v.1)). Its Germanic cognates mostly lurk in compounds that translate as "clove-leek," such as Old Saxon clufloc, Old High German chlobilouh. Dissimilation produced Dutch knoflook, German knoblauch.
cloven (adj.): "divided, split," Old English clofen, past participle adjective from cleave (v.1).
clover (n.): Middle English, from Old English clafre, clæfre "clover," from Proto-Germanic *klaibron (source also of Old Saxon kle, Middle Low German klever, Middle Dutch claver, Dutch klaver, Old High German kleo, German Klee "clover"), which is of uncertain origin.

Klein and Liberman write that it is probably from West Germanic *klaiwaz- "sticky pap" (see clay), and Liberman adds, "The sticky juice of clover was the base of the most popular sort of honey." First reference in English to the suposed luck of a four-leaf clover is from c. 1500. To be in clover "live luxuriously" is 1710, "clover being extremely delicious and fattening to cattle" [Johnson]. Four-leaf clover attested from 1845.
cloverleaf (n.): 1882, from clover + leaf (n.). Highway interchange sense attested by 1933.
Clovis: type of prehistoric stone spearpoints, 1943, from Clovis, New Mexico, U.S., near which place they were found. The town is said to have been named for the Frankish king Clovis (Latinized from Frankish Chlodovech, from Germanic masc. proper name *hluda-wigaz "famous in battle," cognate with Ludwig and Louis).
clowder: 1811, variant of clutter.
clown (n.): 1560s, clowne, also cloyne, "rustic, boor, peasant," origin uncertain. Perhaps from Scandinavian dialect (compare Icelandic klunni "clumsy, boorish fellow;" Swedish kluns "a hard knob; a clumsy fellow," Danish klunt "log, block"), or akin to North Frisian klönne "clumsy person." Or, less likely, from Latin colonus "colonist, farmer," though awareness of this word might have influenced the sense development in English.

Meaning "professional fool, professional or habitual jester" is c. 1600. "The pantomime clown represents a blend of the Shakes[pearean] rustic with one of the stock types of the It. comedy" [Weekley]. Meaning "contemptible person" is from 1920s. Fem. form clowness attested from 1801.
clown (v.): c. 1600, "to play the clown onstage," from clown (n.); colloquial sense of "to behave inappropriately" (as in clown around, 1932) attested by 1928, perhaps from theatrical slang sense of "play a (non-comical) part farcically or comically" (1891). Related: Clowned; clowning.
clownage (n.): "function or manners of a clown or jester," 1580s, from clown (n.) + -age.
clownery (n.): 1580s, from clown (n.) + -ery.
clownify (v.): 1610s, from clown (n.) + -ify. Related: Clownified; clownifying.
clowning (n.): 1861, verbal noun from clown (v.).
clownish (adj.): 1560s, "rustic;" 1580s, "boorish, ungainly, awkward," from clown (n.) + -ish. Related: Clownishly; clownishness.
cloy (v.): "weary by too much, fill to loathing, surfeit," 1520s, from Middle English cloyen "hinder movement, encumber" (late 14c.), a shortening of accloyen (early 14c.), from Old French encloer "to fasten with a nail, grip, grasp," figuratively "to hinder, check, stop, curb," from Late Latin inclavare "drive a nail into a horse's foot when shoeing," from Latin clavus "a nail" (see slot (n.2)).
Accloye is a hurt that cometh of shooing, when a Smith driveth a nail in the quick, which make him to halt. [Edward Topsell, "The History of Four-footed Beasts," 1607]
The figurative meaning "fill to a satiety, overfill" is attested for accloy from late 14c. Related: Cloyed; cloying.
cloying (adj.): 1640s, present participle adjective from cloy (v.). Related: Cloyingly; cloyingness.
cloze (n.): 1953, in psychological writing, evidently abstracted from the pronunciation of closure.
club (n.): c. 1200, "thick stick used as a weapon," from Old Norse klubba "cudgel" or a similar Scandinavian source (compare Swedish klubba, Danish klubbe), assimilated from Proto-Germanic *klumbon, related to clump (n.). Old English words for this were sagol, cycgel. Specific sense of "bat used in games" is from mid-15c.

The club suit in the deck of cards (1560s) bears the correct name (Spanish basto, Italian bastone), but the pattern adopted on English cards is the French trefoil. Compare Danish klőver, Dutch klaver "a club at cards," literally "a clover."

The social club (1660s) apparently evolved from this word from the verbal sense "gather in a club-like mass" (1620s), then, as a noun, "association of people" (1640s).
We now use the word clubbe for a sodality in a tavern. [John Aubrey, 1659]

Admission to membership of clubs is commonly by ballot. Clubs are now an important feature of social life in all large cities, many of them occupying large buildings containing reading-rooms, libraries, restaurants, etc. [Century Dictionary, 1902]

I got a good mind to join a club and beat you over the head with it. [Rufus T. Firefly]
Club soda is by 1881, originally a proprietary name (Cantrell & Cochrane, Dublin). Club sandwich recorded by 1899, apparently as a type of sandwich served in clubs. Club car is from 1890, American English, originally one well-appointed and reserved for members of a club run by the railway company; later of any railway car fitted with chairs instead of benches, and other amenities (1917). Hence club for "class of fares between first-class and transit" (1978).
The club car is one of the most elaborate developments of the entire Commuter idea. It is a comfortable coach, which is rented to a group of responsible men coming either from a single point or a chain of contiguous points. The railroad charges from $250 to $300 a month for the use of this car in addition to the commutation fares, and the "club" arranges dues to cover this cost and the cost of such attendants and supplies as it may elect to place on its roving house. [Edward Hungerford, "The Modern Railroad," 1911]
club (v.): "to hit with a club," 1590s, from club (v.). Meaning "gather in a club-like mass" is from 1620s. Related: Clubbed; clubbing.
CLUB, verb (military). -- In manoeuvring troops, so to blunder the word of command that the soldiers get into a position from which they cannot extricate themselves by ordinary tactics. [Farmer & Henley]
club-fist (n.): 1570s, "a large fist," hence, "a brutal fellow," from club (n.) + fist (n.).
club-foot (n.): also clubfoot, "deformed foot," 1530s, from club (n.) + foot (n.).
club-house (n.): also clubhouse, "place of meeting and refreshment always open to those who are members of the club," 1818, from club (n.) in the associative sense + house (n.). Clubhouse lawyer is baseball slang by 1940s.
clubbed (adj.): late 14c., "shaped like a club," from club (n.). Specifically of defects of the foot by c. 1500; meaning "formed into a club" is from 1620s.
clubby (adj.): "of a social disposition," 1859, from club (n.) in the associative sense + -y (2). Related: Clubbily; clubbiness.
cluck (v.): Old English cloccian originally echoic. Compare Turkish culuk, one of the words for "turkey;" Greek klozein, Latin glocire, German glucken. Related: Clucked; clucking.
cluck (n.): 1703, "sound made by a hen," from cluck (v.). Slang meaning "stupid person" (turkeys are famously foolish) is from 1927.