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 the word slugger, as in someone who hits a ball strongly, comes from the Irish word slacaire, which means a hitter or a batsman (slacaí in modern Standard Irish) and that to slug comes from the verb slacadh. On the face of it, this seems like a convincing claim but if you examine it more closely, it becomes less clear.
Firstly, let’s look at slug as a word for hitting. The English dictionaries agree that it is related to slog (as in ‘a hard slog’) and that its origin is unknown. For the word slog, its first recorded use in English is apparently in 1824, while slug is even later, in 1830. The Irish word slacadh apparently comes from slaic (slacán) which means stick or bat.
The problem is this. Slog looks Germanic. It looks and sounds as though it is related to the German schlagen or the Yiddish shlogn. In other words, it looks like either an ancient English dialect word which was unrecorded or a loanword from German or Dutch.
My main reason for being sceptical of Cassidy’s claim is that slacadh sounds very different from slog or slug. The sl is the same, but if English borrowed the word slacadh without changing the sound, you would have a great batsman described as a slacker, who really slacks the ball! Slog could have been borrowed into English from Irish, but it means to swallow. Both slack (slac) and slog (slog) are perfectly easily pronounced words in both English and Irish, so there would be no reason for them to become confused or mangled.