I found the following in Wikipedia:
Irish speaking Dopers, is this accurate?
The origin of kibosh is the subject of much discussion, but the candle snuffer theory sounds like a good candidate. Trouble is, I’ve not heard it anywhere else. I’m a bit dubious.
Specific questions:
Which is the accurate transcription, an chaip bháis or caip bháis, or are they separate phrases?
is it accurately pronounced the same as kibosh in English?
Was the term really used for a candle snuffer?
The esteemed Michael Quinion, editor of World Wide Words has a lengthy piece on the word in which he concludes “Someday perhaps, some earnest researcher will find more information about the word that ties its origin to one of these explanations, or one nobody has yet thought of, which will really put the kibosh on all this speculation.”
This comes after he pours cold water on the Turkish origin and makes the point that nobody can agree what the original kibosh actually was, except that it was something unpleasant.
He supports the idea of a Yiddish base and is not keen on the Irish derivation. He doesn’t mention candle snuffers, also called douters.
I am already aware of the above. For this particular thread, I’m not interested in other proposed etymologies. Just checking the plausibility of the candle snuffer claim.
I know a tiny amount of Irish, and I’ve had a quick look. “An chaip bháis” would mean “the death cap”, and “caip bháis” would mean “death cap”, were “caip” an actual Irish word, which it doesn’t seem to be. It would be pronounced closer to “kivosh” than “kibosh” .
This article has a bit more information.
Unfortunately I’ve no idea about the candle snuffer claim.
I call folk etymology. This seems extraordinarily unlikely, not least because I’ve never seen that phrase in Irish. For one thing, the word for “cap” is caipín, not caip. Here’s a good site on this subject (Irish-language article at the top; for English, scroll down).
An is the definite article (“the”), so either phrase is correct. It can sometimes cause that -h to appear, but this makes it look like caip is a feminine word, which I don’t think it would be.
AFAIK in the UK this is late 19th/early 20th century slang (cf. the WW1 music hall song Belgium Put The Kibosh On The Kaiser). I doubt whether many Gaelic (Irish or Scottish) words would have made it into the ken of the kind of British people who used that sort of slang.
Maybe there was a different route elsewhere in the English-speaking world, but in the UK, I’d think it more likely either some derivation from Yiddish, or soldiers’ mangling of a word from some other language encountered elsewhere in the Empire (Hindi, or maybe even Afrikaans, from the South African War). But that’s just a guess.
The Irish phrase “caidhp bháis” meaning death cap (mushroom) is in Ó Dónaill’s dictionary. It literally means “cap of death” so presumably is a calque of the English word.
The words would be pronounced something like “kipe vosh” and could easily be heard as “kibosh” by an English speaker.
I have no idea whether the phrase was used for a candle snuffer. The mushroom meaning is the only meaning given in the dictionary.
I found an interesting article online discussing the supposed Irish origin of kibosh:
caidhp an bháis | cassidyslangscam (wordpress.com)
The blog is subtitled “A debunking of Daniel Cassidy’s theories about the influence of the Irish language on English slang”, so it’s no surprise that the writer takes a sceptical view of this claimed etymology.