I grew up avidly watching Hockey Night in Canada, which means my sense of the English language was forever affected by the voice of Danny Gallivan. A Nova Scotian of Irish descent, he spent more than 30 years as the play-by-play announcer of the Montreal Canadiens. Gallivan is said to have coined “spinarama,” a complete twist so as to elude another player. He didn’t invent “donnybrook” — “a scene of uproar and disorder,” to quote the Oxford Dictionary of English, and a word by which Gallivan often evoked a brawl on ice — but I’ve seldom heard the term from anyone else’s lips. Donnybrook is a neighbourhood in south Dublin that was once notorious for dust-ups at its annual fairs.

In the literary world there are skirmishes, there are battles, and there are full-throated donnybrooks. One of those donnybrooks arose after the appearance in 2007 of a book titled How the Irish Invented Slang: The Secret Language of the Crossroads. Its author, Daniel Cassidy, had founded the Irish Studies Program at New College in San Francisco; he also worked as a journalist, a documentary filmmaker and a musician. Cassidy claimed that much of American slang emerged from Irish Gaelic — “a back-room language,” he told the New York Times, “whispered in kitchens and spoken in the saloons” — and he charged that prejudiced mainstream lexicographers had chosen to ignore the impact of Gaelic.

Cassidy told the kind of story people like to believe. An underdog language, suppressed by Ireland’s British rulers in the 19th century, crossed the Atlantic and, by its usage in saloons, brothels, political backrooms and other unsavoury places, gave birth to dozens or even hundreds of American expressions. The author suggested, for instance, that “slum” can be traced back to the Gaelic “s’lom” (bare, naked, poor), and “kibosh” to the Gaelic “caidhp bhais” (death cap mushroom). Cassidy even found Gaelic origins for a pair of quintessentially American words, “jazz” and “dude.” Jazz, he stated, is not an African-American term as people generally believe; it comes from “teas,” a Gaelic noun for passion, heat, excitement. The critics lapped it up: How the Irish Invented Slang won the American Book Award for non-fiction.

Trouble is, not everyone could embrace its arguments. In the eyes of Grant Barrett, a leading American lexicographer, “Cassidy’s theories are insubstantial, his evidence inconclusive, his conclusions unlikely, his Gaelic atrocious ... and his scholarship little better than speculation. In short, his book is preposterous.” That’s one hell of a bad review of an award-winning title. Unfortunately, Cassidy is not around to defend himself; he died of pancreatic cancer a year after the book was published.

The crux of the matter is that Cassidy relied almost exclusively on phonetic similarities between Gaelic and American words. But similarities are not the same as actual proof. He proposed, for example, that “bunkum” — old-fashioned American slang for nonsense — comes from the Gaelic “buanchumadh” (a long, made-up story). It sounds plausible. But the notion goes against much hard and clear evidence that bunkum is derived from Buncombe, a county in North Carolina. In 1820, its representative in the state legislature gave a long, rambling speech and, when asked to sit down, replied: “I am talking for Buncombe!” Within a few years “bunkum” had become a byword for political hot air. As for “clamour,” Cassidy rightly noted that it resembles a Gaelic term — but he neglected to mention that it has been an English word since the 14th century.

Barrett and other critics have pointed out many such flaws, yet Cassidy’s book remains in wide circulation and still has passionate defenders. I suspect his basic point is valid: Gaelic probably does lie at the root of much American slang. It’s a pity that a book making this point so powerfully is also undermined by dubious research and wild speculation.

In my last column I described some distortions of the English language, especially in commercial names: Toys R Us, Krispy Kreme, Chick-fil-A and the like. Bruno Paul Stenson wrote to say that years ago, when he was “working at a teachers’ supply store in the Fairview Shopping Centre, a francophone customer who had not found what she was looking for turned to her friend and said: ‘On va aller chez Toys Russes’.” I have to admit I like the idea of Montrealers turning an American behemoth into a Russian boutique.