Old English cetil (Mercian), from Latin catillus "deep pan or dish for cooking," diminutive of catinus "bowl, dish, pot." A general Germanic borrowing (cf. Old Saxon ketel, Old Frisian zetel, Middle Dutch ketel, Old High German kezzil, German Kessel). 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.
A steep, bowl-shaped hollow in ground once covered by a glacier. Kettles are believed to form when a block of ice left by a glacier becomes covered by sediments and later melts, leaving a hollow. They are usually tens of meters deep and up to tens of kilometers in diameter and often contain surface water.