Putting The Kibosh On Cassidy

In Daniel Cassidy’s worthless book of fake etymology, he claimed that the word kibosh or kybosh is of Irish origin. Cassidy was certainly not the first to claim this and his sole authority for saying it was a website called Cork Slang Online. The usual claim in relation to its supposed Irish origin is that it comes from caidhp bháis or caidhp an bháis or caip bháis, meaning a cap or cape of death. Some sources also mention cie báis, but cie is not a possible word in Irish orthography.

While caidhp bháis is given as the name of a fungus in Irish dictionaries (the death cap), there is no evidence that this is an ancient expression and it may have been composed on the pattern of the English phrase death cap in the 20th century.

There are various explanations for the meaning of caidhp bháis as a possible origin of kybosh. Some people say that it was the black cap used by a judge when pronouncing the death sentence. (I would use caipín dubh, though it doesn’t seem to be in any dictionary.) Others say that it is from the pitch cap, a punishment used by the British in Ireland where a cap of burning pitch was placed on a person’s head. This is more commonly a caipín pice in Irish. On line, I have also found claims that the caidhp bháis was a word for a candle snuffer or smóladán. There seems to be no independent evidence for any of these claims.

Only the mushroom explanation is in the dictionaries. Corpas na Gaeilge (a huge corpus of Irish material from the seventeenth to the nineteenth centuries) gives a number of examples of caidhp but nothing with caidhp bháis or caidhp an bháis.

We don’t know who first suggested this Irish origin. Charles Earl Funk said that he received this information in a letter from the poet Pádraig Colum. This is not dated but could have been in the 1930s, 1940s or 1950s. However, the earliest certain reference is in the Cornell Daily Sun from the first of December 1936, where there is an account of a lecture by a man called Conboy about the Irish origin of English words. He gives words like shanty and quid (as in a quid of tobacco, which he derives from Irish cuid, a piece) as well as kibosh.

“Kibosh,” Conboy said today, “comes from ‘caip,’ which means cap, and bais,’ which means death. “It originated in Ireland about the time of Judge Norbury, who was called the ‘hanging judge.’ When the people would see him reaching for the black cap he wore when giving the death sentence, they would say: ‘The prisoner is ‘ finished. The judge Is putting on the caip bais – kibosh. Thus when we say we ‘put the kibosh on something,’ we mean we have disposed of it.” (Editor’s note: Some authorities hold that “kibosh” might be of Yiddish origin.)

Strangely, while there is no evidence of caidhp bháis being used in the language long ago, there is certainly evidence of its existence in the language now. For example, there is this, from an article by Donncha Ó hÉallaithe in the online journal Beo in 2012:

Trí dhiúltú do na logainmneacha a bhí ar bhéal na ndaoine, rinne an Donnabhánach a chuid féin, chun caidhp an bháis a bhualadh ar an nGaeilge sa gcuid mhór den tír ina raibh an Ghaeilge in uachtar roimh an Drochshaol. (By rejecting the placenames which were in popular use, O’Donovan did his own bit to put the kibosh on the Irish language in the large area of the country where Irish was in the ascendant before the Famine.)

Unfortunately, this proves nothing. The story of the Irish origin of kibosh is so common and well-known that it is hardly surprising that people have started to use the terms caidhp bháis or caidhp an bháis in Irish in recent years. It sounds convincing and natural enough. However, without some evidence of its use in Irish before speculation about kibosh began, we can’t accept these modern uses as evidence for an Irish origin of the phrase.

There are various theories about the real origin of the word kibosh. You will find an account of these different theories by following this link:



4 thoughts on “Putting The Kibosh On Cassidy

  1. David L. Gold

    Your link to World Wide Words takes the reader to mention of this article of mine:

    Gold, David L. 2011. “After at least 138 years of discussion, the etymological puzzle is possibly solved: the originally British English informalism kibosh as in “put the kibosh on [something]” could come from the clogmakers’ term kybosh ‘iron bar which, when hot, is used to soften and smooth leather’ (with possible reinforcement from Western Ashkenazic British English khay bash ‘eighteen pence’)”. Revista Alicantina de Estudios Ingleses. No. 24. Pp. 73-129.

    I no longer believe that the clogmakers’ term may be the etymon of kibosh as in put the kibosh on […] or that the word kibosh as in put the kibosh on […] may have a slight Jewish connection. Kibosh has no Jewish connection, whether Hebrew, Yidish, or any other kind.

    That article, however, is still useful because:

    1. It clears away heaps of misinformation that have accumulated in connection with the alleged, never proven, and, in fact, impossible Yidish or Hebrew origin of the word.

    2. It sets the record straight on the misprint “kibosk,” and

    3. It corrects mistakes in the entry for the word in The Oxford English Dictionary.

    The entire text off the article is available free online.

    Is it known what the pitch-cap was called in Irish during the Irish Rebellion of 1798?

    1. DebunkerOfCassidy Post author

      Hi David, Welcome to the blog! You should also check out my recent post on the same subject, More on the Irish origins of kybosh. Use the search box at the side. Wherever kybosh comes from, an Irish origin seems fairly unlikely. The claims of caidhp bháis meaning a pitch cap or a judge’s black cap or a cowl on a shroud seem to be of recent origin. The claim about caidhp bháis was first made in 1909, where it was ascribed to an Irish language expert who promptly answered that claim in the same newspaper and denied that he had ever said anything about caidhp bháis! The Italians have a term, I think it is etruscheria, which describes the fanciful nonsense which people have made up surrounding the Etruscans. I think languages like Irish and Yiddish are often subject to the same forces, where enthusiasts and eccentrics pin the same kind of nonsense to them without the slightest evidence. I hope that someday, someone comes up with a clear smoking gun for kybosh. At the present state of knowledge, there is no reason, in my opinion, to regard it as a phrase of Irish origin.


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