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.
According to Cassidy, the English word sneak comes from the Irish snighim (sním in the modern, post-reform spelling) but apparently, sneaky comes from the adjective snagach (snaggah). This sounds nothing like sneaky and is not etymologically related to snighim. In reality, the mainstream dictionaries trace it, quite logically, to the Old English snican which is related to cognates in the other Germanic languages as well as to the root of the English word snake.