American Heritage Dict.
kibosh - Informal. A checking or restraining element: had to put the kibosh on a poorly conceived plan [origin unknown]
Merriam Webster's says the same and gives 'kybosh' as a chiefly British variant.
Maybe you can find some interesting references on the net using these spelling variants.

In Alfred H. Holt's "Phrase and Word Origins" [New York: Dover Publications] I found s.v . "kibosh" the following : A Mr. Loewe, who ought to know wrote to N. & Q. ["Notes and Queries"] that this is a Yiddish word formed from four consonants, representing eighteen-pence. When at a small auction, an eager bidder jumped his offer to eighteen pence, he was said to have "put the kibosh" on his fellow-bidders. B.&L. [Barrère and Leland, "Dictionary of Slang"] may have confused it with "bosh" in explalning it as "nonsense, rubbish." In 1836 it appeared as "kye-bosk," in 1856 Dickens used it, but it had not by 1891 become sufficiently naturalized to divest itself of quotation marks. ---
The Oxford Dictionary of Quotations [Major New Edition] has one entry with the word "kibosh" , "Belgium put the kibosh on the Kaiser", title of a song. (1914).
By the way, one of the German equivalents of "put the kibosh on sthg." is "vermasseln". a Yiddish word, derived from "massel", "Glück."

kibosh= Blödsinn

put the kibosh on= ein Ende machen, erledigen

to put the Kybosh on sth.

Would ruin the chances of something happening...
Would bring the chances of something happening to an end

Eg. I was going to have a BBQ, but the bad weather put the kybosh on that idea.