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.
Daniel Cassidy, in his work of etymological fiction, How The Irish Invented Slang, claimed that the term kook, meaning a nutcase or earlier a fool, comes from the Irish word cuach, meaning a cuckoo, rather than directly from the English word cuckoo.
The use of cuckoo to mean a fool dates back at least four hundred years in English. The association with madness is much more recent.
Cassidy defines the Irish word cuach as “a cuckoo, a squeaky voice, a fool”. He repeats this claim about cuach meaning fool twice, and he claims Dinneen’s dictionary as his source. This is strange, as neither edition of Dinneen mentions fool as a meaning of cuach. It is not mentioned as a meaning in Ó Dónaill’s dictionary either, as you can see from the links below.
This is a link to the 1904 edition of Dinneen:
This is a link to the 1927 edition of Dinneen:
This is Ó Dónaill’s take on the meanings of cuach:
In other words, why would kook meaning fool or madman have come from Irish cuach, when Irish cuach doesn’t have the meaning of fool or madman and this claim was simply invented by Cassidy?
I should also point out that the word cuach doesn’t sound much like kook but don’t take my word for it. Check out the sound files here: