"metal vessel used for boiling or heating liquids over a flame," Old English cetil, citel (Mercian), from Proto-Germanic *katilaz (compare Old Saxon ketel, Old Frisian zetel, Middle Dutch ketel, Old High German kezzil, German Kessel), which usually is said to be derived from Latin catillus "deep pan or dish for cooking," diminutive of catinus "deep vessel, bowl, dish, pot," from Proto-Italic *katino-.
This word has been connected with Greek forms such as [kotylē] "bowl, dish." Yet the Greek word is no perfect formal match, and words for types of vessels are very often loanwords. It seems best to assume this for catinus too. [de Vaan]
One of the few Latin loan-words in Proto-Germanic, along with *punda- "measure of weight or money" (see pound (n.1)) and a word relating to "merchant" that yielded cheap (adj.). "[I]t is striking that all have something to do with trade" [Don Ringe, "From Proto-Indo-European to Proto-Germanic," Oxford 2006]. Perhaps the Latin word was confused with a native Germanic one.
Spelling with a -k- (c. 1300) probably is from influence of Old Norse cognate ketill. The smaller sense of "tea-kettle" is attested by 1769.
Kettle of fish "complicated and bungled affair" (1715), sometimes is said to be from a Scottish custom of a kettle full of fish cooked al fresco at a boating party or picnic, but this custom is not attested by that phrase until 1790. Perhaps it is rather a variant of kittle/kiddle "weir or fence with nets set in rivers or along seacoasts for catching fish" (c. 1200, in the Magna Charta as Anglo-Latin kidellus), from Old French quidel, probably from Breton kidel "a net at the mouth of a stream." Kettle was used in geology for "deep circular hollow in a river bed or other eroded area, pothole" (1866), hence kettle moraine (1883), characterized by such features.
"very large kettle or boiler," c. 1300, caudron, from Anglo-French caudrun, Old North French cauderon (Old French chauderon "cauldron, kettle"), from augmentative of Late Latin caldaria "cooking pot" (source of Spanish calderon, Italian calderone), from Latin calidarium "hot bath," from calidus "warm, hot" (from PIE root *kele- (1) "warm"). The -l- was inserted 15c. in imitation of Latin.
"cavity on the summit of a volcano," 1865, from Spanish caldera, literally "cauldron, kettle," from Latin caldarium "hot-bath" (plural caldaria), from caldarius "pertaining to warming," from calidus "warm, hot" (from PIE root *kele- (1) "warm"). A doublet of cauldron.
The term was originally used in describing volcanic regions occurring where Spanish is the current language, and was introduced by Von Buch in his description of the Canaries. [Century Dictionary]
early 13c., from Anglo-French bascat; of obscure origin despite much speculation. On one theory, it is from Latin bascauda "kettle, table-vessel," said by the Roman poet Martial to be from Celtic British and perhaps cognate with Latin fascis "bundle, faggot," in which case it probably originally meant "wicker basket." But OED frowns on this, and there is no evidence of such a word in Celtic unless later words in Irish and Welsh, sometimes counted as borrowings from English, are original. As "a goal in the game of basketball," 1892; as "a score in basketball," by 1898.
"deep, circular vessel," from late Old English pott and Old French pot "pot, container, mortar" (also in erotic senses), both from a general Low Germanic (Old Frisian pott, Middle Dutch pot) and Romanic word from Vulgar Latin *pottus, which is of uncertain origin, said by Barnhart and OED to be unconnected to Late Latin potus "drinking cup." Similar Celtic words are said to be borrowed from English and French.
Specifically as a drinking vessel from Middle English. Slang meaning "large sum of money staked on a bet" is attested from 1823; that of "aggregate stakes in a card game" is from 1847, American English.
Pot roast "meat (generally beef) cooked in a pot with little water and allowed to become brown, as if roasted," is from 1881. Pot-plant is by 1816 as "plant grown in a pot." The phrase go to pot "be ruined or wasted" (16c.) suggests cooking, perhaps meat cut up for the pot. In phrases, the pot calls the kettle black-arse (said of one who blames another for what he himself is also guilty of) is from c. 1700; shit or get off the pot is traced by Partridge to Canadian armed forces in World War II. To keep the pot boiling "provide the necessities of life" is from 1650s.