Tag Archives: origin of kybosh

Cassidese Glossary – Kabosh, Kybosh

For some time now, some of my on-line friends have advised me to provide a version of CassidySlangScam without the invective aimed at Cassidy and his supporters. In response to that advice, I am working on providing a glossary of the terms in Cassidy’s ludicrous book How The Irish Invented Slang with a short, simple and business-like explanation of why Cassidy’s version is wrong.

I have posted before about the supposed Irish origins of the phrase ‘to put the kybosh on something’. In a post called Putting The Kybosh On Cassidy (May 2016) I pointed out that kybosh has often been claimed to be of Irish origin, a corruption of caip bháis or caidhp bháis, meaning death cap. The usual explanation for this is that it refers to the black cap donned by a judge when passing the death sentence, though other claims include that it refers to a method of torture used by the English called pitch capping, or to a part of a shroud that covers the face of the dead. There is no evidence for the phrase caip bháis existing in Irish at all, and caidhp bháis is only used in the late 20th century as the name of a fungus known as the death cap in English.

Cassidy found the claim about the Irish origins of kybosh online and included it in his book but it is clear that this particular mythical etymology predates Cassidy by almost one hundred years.

We don’t know where the word kybosh really comes from. You can find an interesting discussion of the term kybosh by Anatoly Liberman on the OUP blog:


As I stated in another blog post, More On The Irish Origins of Kybosh, I found an explanation for the myth about the Irish origins of the word in the Irish Newspaper Archive. The earliest references to the word in Irish newspapers were in 1909. They were also by far the most interesting. In an article called An American Professor on England published on November 29th 1909, an anonymous staff author of the Freeman’s Journal wrote:

Many expressions familiar in American-English are clearly translations or adaptations from the Gaelic: not a little slang was good idiomatic Gaelic, and such an extraordinary word as kybosh – “to put the kybosh on a man or a scheme” – takes a very curious interest when, as Mr J.H. Lloyd tells in one of his invaluable vocabularies to Irish poems or stories – it is traced to the extinct phrase “the cap of death” – i.e. the black cap of the hanging judge.

J.H. Lloyd, or Seosamh Laoide, was an Irish language expert. However, Lloyd himself then replied to this on December the 2nd in the Freeman’s Journal, complaining that his views had been misrepresented:

Dear Sir – In your issue of 29th November, one of your leader writers, towards the end of the article “An American Professor on England”, quotes me in connection with the word “kybosh”, to put the kybosh on a man or a scheme. So far, he is correct. When, however, he adds the explanation “the cap of death,” apparently attributing this to me, he is very much astray.

In the vocabulary to Mac Mic Iasgaire Bhuidhe Luimnigh, published by the Gaelic League, I set down that caidhp bathais, to my surmise an expression of the lost Leinster dialect of Irish, was the probable etymon of “kybosh”.

He goes on to say that caidhp bathais would mean the cap or coif of the crown of the head. He says that kybosh could not come from caidhp báis because the o of kybosh is a short vowel. He states clearly that he has never actually found an example of this phrase in use in the Irish language (“though I have failed to find the word in use in an Irish dress”). In other words, the myth about caidhp bháis can be traced to one mistaken reference in 1909 and has been repeated endlessly ever since.

However, while there are plentiful uses of kybosh, coybosh and even caidhp bháis in the Irish papers from the second decade of the 20th century until the last few years, there are absolutely no traces of caidhp bháis, caip bháis, caidhp bhathais or caip bhathais (or any of the versions without the séimhiú which modern Irish grammar would require) anywhere before the 1909 references. This is 75 years after kybosh’s first appearance in England. And we need to note that many expressions like spraoi and craic have made their homes in the Irish language and been accepted as intrinsic and ancient parts of that language by its speakers, even though they aren’t.