Etymology
1. The origin of the noun is uncertain; the following etymologies have been suggested:
2. * According to Gerald Leonard Cohen, Stephen Goranson, and Matthew Little, at present the most likely derivation is as a non-rhotic variant of kurbash (“heavy whip, lash”), from Arabic كُرْبَاج (kurbāj, “lash, whip”), or from its etymon Ottoman Turkish قرباچ (kırbaç, “lash, whip”) (whence Turkish kırbaç (“whip”)).
3. * From Irish caidhp bháis (literally “death cap”), said to denote, among other things, the black cap worn by English judges when pronouncing the death sentence, the hood put on a person before they were put to death by hanging, or a form of torture called pitchcapping. However, there appears to be no convincing evidence that the term was used in these senses.
4. * From a Yiddish word (compare Hebrew כָּבַשׁ (kavásh, “to conquer, subjugate”)); however, no such word has been found.
5. * From Middle English cabochen (“to cut off (the head, chiefly of a deer), behead”), from Middle French cabocher (“to cut off (the head)”), from caboche (“the head”) (Northern France, informal) (whence Middle English caboche (“head of cabbage”)), from Italian capocchia (“the head”) (derogatory), ultimately from Latin caput (“the head”). The Middle English word is said to have been adopted in Cockney slang; however, how this is supposed to have happened remains unexplained
6. * A clogmakers’ term kibosh (“iron bar about a foot long that, when hot, is used to soften and smooth leather”).
7. The verb is derived from the noun. See: Middle English Nouns '
caboche', Italian Nouns '
capocchia', Latin Nouns '
caput'.