According to Daniel Cassidy, the King of the Irish-American Liars, the term ‘billy club’ (a policeman’s truncheon) comes from Irish. The orthodox dictionaries tell us that this is an American term first recorded in 1848, and was originally burglar’s slang for ‘a crowbar’. According to these sources, it is probably derived from the personal name William/Billy, on the analogy of terms like jack and jimmy and jemmy and jenny, all of which also meant crowbar. Cassidy (of course) disagrees with the experts. According to him it is a buille club, with buille being the Irish for ‘blow, stroke, hit, whack’.
Let’s just examine this claim carefully. Firstly, what is the Irish for club? Dredging words up from my own memory, there is bata, sail éille, cleith ailpín, maide and smachtín. A search of the dictionaries also brings up words like lorga and lorgaid. However, it seems bizarre to put the word for blow next to any of these words, just as it would seem strange to talk about a blow-club in English. I mean, what other kind of club is there? A wave-around-in-the-air-in-a-menacing-fashion-for-a-few-minutes-then-put-it-back-in-the-cupboard-club? Or a pointy stab-club, which some people refer to as a sword? And buille is pronounced bwullya, which really isn’t that close to billy anyway.
In short, this is just as stupid as the rest of this idiotic book. The orthodox claim, as given on etymology sites and in dictionaries, is far more likely than Cassidy’s nonsense.