The book Origin of Kibosh (which is a real book since it’s available online), quoted in a post above, says that it comes from something a Cockney chimney sweep says in 1834. He said, “it vos the Vigs vot passed this bill, and vot the Duke of Vellington put the kibosh on ‘em for, and sarve ‘em right. It warnt nothing else than this here hact vot floored them.” Cockneys are relatively poor people of London, and the following are translations of the term they use in this case. It really looks like it comes from a Cockney word:
vots = was
Vigs = Wigs
vot = what (which means “which” in this sentence)
Vellington = Wellington
'em = them
sarve = serve
warnt = wasn’t
nothing else = anything else
this here hact = this act
floored = knocked to the ground
I know Hawkeye said something to Potter about “putting the kibosh on the Kaiser”, referencing the action Potter saw in Europe; that episode was on MeTV relatively recently.
Here’s a way to read the first known uses of the word “kibosh” in print. Do a search on Google for the phrase “Vellington put the kibosh”. Be sure to put quotation marks around that phrase. When I do it, a page appears (sort of floating) in front of a website. It says that the word “kibosh” appears for the first time on various pages of various British newspapers in November and December of 1834. Apparently you have to pay to actually read that page. Pay for it and read it. Tell us what those articles in those newspapers say.
What about the pronunciation? I thought it was pronounced ki-BOSH (“ki” like kid or kick, rolled together in what sounds like a Yiddish pronunciation) but then I heard more people say KI-bosh (“KI” like kind or kite, in what sounds like two words).
The latter pronunciation was what I learned as a kid. Although I have heard people (mostly northeasterners) use the former.
If it really did have a Yiddish origin, or if people mistakenly assumed it did, I could sure see them adjusting the pronunciation to be more authentically Yiddish-sounding.