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.
Nobody is sure of the origin of shack, meaning a rough hut or shed. Some sources link it to a Mexican term which is derived from Nahuatl, the language of the Aztecs.
Others link the word shack to English dialect variants of shake. Still others point to the existence of words like ramshackle.
Daniel Cassidy, in his etymological hoax How The Irish Invented Slang, claims that this word represents the Irish teach, which means a house (not a shed or a shack, which would be expressed with words like bothán, cró or seid in Irish.
There is also a problem with pronunciation. Here is a link to sound files for the pronunciation of teach in the three main dialects of Irish:
He also gives a separate entry for shack in the sense of a caboose of a train, which he says also comes from the Irish word teach.