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.
Cassidy claims that ‘smashing!’ as in ‘It was a smashing day!’ comes from the Irish or Scottish Gaelic phrase ‘is maith sin’ (iss mah shin), meaning that is good. The phrase does exist but so does the English word smash, and there are many similar expressions, such as a belter, or bostin’ (busting, a Midlands English expression) or indeed, a hit, where the act of hitting or beating expresses success. Whether this claim is true or not, it is a well-known piece of folk-etymology in Ireland and Scotland and dates back long before Cassidy.