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.
The origins of the word knack are unknown but it seems to have been used in its present sense as a special talent or skill by the late 16th century.
According to Daniel Cassidy, in his work of false etymology, How The Irish Invented Slang, the word knack comes from the Irish word gnách. The word gnách is an adjective meaning customary, usual or ordinary. It is most commonly used in copular phrases like is gnách leo (they tend to, they have the habit of). Gnáth is a noun meaning custom, usage or customary thing and it is true that the two words sound almost identical and are often confused.
There are several problems with Cassidy’s claim. Firstly, while gnáth or gnách could theoretically be used as nouns to refer to a custom or ordinary usage, this would rarely be the case. Such uses would normally be expressed in Irish with nós (bhí nós aici bláthanna a chur san fhuinneog, bhí sé de nós aici bláthanna a chur san fhuinneog) or with a copular structure (ba ghnách léi bláthanna a chur san fhuinneog).
Secondly, a knack is not a custom. The meanings may be slightly similar but they are certainly not the same. In Irish, a knack is cleas, or bealach, or dóigh, or ciúta. It’s a special skill or trick or way of doing something. When you do something a lot, you may acquire a skill in doing it. But the two concepts are not the same.
This really cuts to the heart of why Cassidy’s ‘research’ is so worthless. As I have said before, the central problem is one of the mechanism of transmission. It’s all very well making a link between an Irish word with a particular meaning and an English word with a different but related meaning. It is much harder (in fact, it’s usually impossible) to imagine a situation where a bilingual Irish and English speaker would use the wrong word in any circumstance and this would be borrowed with a different meaning. Why would this happen? How would it happen?
Finally, gnách really doesn’t sound much like knack. You can find sound files for the dialects of Irish here:
https://www.focloir.ie/en/dictionary/ei/customary#customary__2
cassidyslangscam 