This is another term that Cassidy invented an Irish ‘origin’ for in his crazy book How The Irish Invented Slang. Honky-tonk was first recorded in the late 19th century. It originally meant a cheap saloon. Cassidy derives it from the Irish phrase aingíocht tarraingeach, which he claims means ‘attractive wickedness.’ Let’s examine how likely it is that aingíocht tarraingeach would be used by an Irish speaker to refer to a pub.
First, there is the minor but telling point that in the Irish language, feminine nouns lenite the adjective following, so, it would have to be aingíocht tharraingeach. It’s minor because it doesn’t affect the pronunciation much but it is telling in that it shows that even basic Irish grammar was a mystery to Cassidy.
What does aingíocht mean? WinGléacht defines it as ‘malignancy, peevishness’. In other words, it’s not evil in the tempting sense of moral depravity and occasions of sin, it’s someone kvetching at you and treating you like shit.
Tarraingteach (tarraingeach according to Dinneen) does mean attractive.
So, you’re an Irish-speaker in 19th century New Orleans. You have a couple of coins in your pocket so you slap your mucker on the back and say, “Let’s head out to the attractive peevishness at the end of the street”. And in time, everyone calls it the attractive peevishness and so an-gee-okht tah-ring-yakh becomes honky tonk.
Yeah, that’ll be right, mar dhea! (Mar dhea is roughly equivalent to NOT!) But why is Cassidy’s stupid suggestion any more likely than the dozens of other things you could make up which have the same shadowy phonetic similarity? Why not anchaoi thonnach, a billowy bad way, because that’s how you end up after a night there? Or thiontaigh tancaird ‘tankards turned fig. upturned or emptied’? Or, as these places were often brothels too, what about the Scottish Gaelic thàinig è, taing? (‘He came, thank you!’) Of course, I’m being facetious here, but I’m not being any dafter on purpose than Cassidy was unintentionally.
Back in the real world, far from the Magic Kingdom of Cassidia where fantasies become true, honky tonk is thought to be a reference to the kind of music that was played in these low dives, with the honking of horns and the tonk of pianos. Which could be right or it could be wrong but it’s certainly a lot more convincing than Cassidy’s ‘attractive peevishness’ where beer is sold … which, now I come to think of it, probably comes from bia áir, ‘food of massacre!’