Daniel Cassidy, in his insane work of fake etymology, How The Irish Invented Slang, tried to convince people that he had made a major discovery. This discovery was that the Irish language didn’t die out in America and had a massive influence on the speech of ordinary Americans, a contribution which has been ignored by snobbish scholars and lexicographers and apparently went unnoticed even by Irish linguists and academics who could actually speak the language. Cassidy, who didn’t have any qualifications at all, and knew no Irish, was a fantasist and liar and con-man. Most of the supposed ‘Irish’ candidates for the origins of slang terms were made up by Cassidy himself. There is no evidence for their existence.
Even after years of debunking this pompous rubbish, I can still open his book and quickly find another example of the kind of puerile crap that demonstrates that Cassidy, far from working like a true scholar, was more like a toddler playing with fuzzy felt.
For example, Cassidy claims that the English slang term pash comes from Irish:
Pash, n., a long and enthusiastic kiss; passion. “Australian and New Zealand term for French or tongue kissing. Used mainly by teenagers and preteens. Used also in a situation so that adults won’t know what they are talking about …” (Urban Dictionary Online.)
Páis [pron. pásh], n., passion.
Apart from the obvious point that pash is just as likely to be a shortening of English passion rather than anything from Irish, we should also remember Cassidy’s total ignorance of the Irish language and his willingness to doctor and distort the material he found in dictionaries to convince badly-educated people of his case. Here’s what Ó Dónaill’s Foclóir Gaeilge-Béarla has to say about the word páis:
páis, f. (gs. ~e). Passion, suffering. An Pháis, P~ Chríost, P~ ár dTiarna, the Passion (of Christ, of Our Lord). Domhnach, Seachtain, na Páise, Passion Sunday, Week. An Pháis a léamh, to read the Passion (from the gospels). ~ oíche a fhulaingt, to endure a night of travail, of suffering.
In other words, páis is used pretty much exclusively in the religious sense of a crucifixion or a torment. There is another word, a straight Gaelicisation of the English passion (and pronounced the same), paisean. It is this word – or a native equivalent like tocht – which is used for strong emotions like love or desire, not the word páis.