According to Cassidy, the terms ‘brag’ and ‘braggart’ in English derive from the Irish words bréag and bréagóir.
So, is there any truth to this claim? Well, the word bréag does exist in Irish and the word bréagóir is given as a variant (by Dineen) of the more common expression bréagadóir. O Dónaill’s dictionary doesn’t even mention bréagóir as an alternative version. The problem is that while both of these expressions, bréag and bréagadóir/bréagóir, are somewhere in the ballpark, they are out with the hot-dog sellers rather than in the diamond. Bréag means ‘a lie’. It doesn’t mean the same thing as bragging or boasting. There are a number of expressions for bragging: ag déanamh mórtais, ag braigeáil (a loan word from English brag!), maíomh a dhéanamh as rud, ag déanamh a mhór díot féin and half a dozen others.
And, as it happens, brag is well attested in English as far back as the 14th century, which means that it didn’t come from bréag and has nothing to do with Irish slang in America.
And finally, let’s all have a good laugh at Cassidy’s expense. Bréag is pronounced brayg, to rhyme with Haigue or Craig. Broadly speaking, there are two ways of doing the phonetics in books like this. You can either learn the International Phonetic Alphabet and use it as the basis for your description, which looks a bit off-putting to anyone without linguistic training, or you can produce an ad hoc system of your own based on English, as I did with brayg above.
This is the IPA version: bʲɾʲeːɡ. At least, I think this is right. I’m no expert!
Cassidy wrote b’ríǒg as his version of the phonetics of the word bréag. Nobody trying to work out the pronunciation of bréag would have a chance of pronouncing it properly from this. While it looks as technical and scientific as the IPA, it is complete nonsense. Pure codology. God alone knows what Cassidy thought he was doing when he produced this silly little piece of pseudo-phonetics but it just goes to show what a complete charlatan, doofus and moron he was!
These words, of course, are all Irish: síorliodán meaning ‘an eternal rigmarole’, dubhfhios meaning ‘black knowledge’ or figuratively, ignorance, and mór-rón, a big fat stupid seal. Obviously, none of these is really correct but it just shows how easy it is to produce crap like this using Cassidy’s ‘methodology!’
Chance of Cassidy being correct: Surprise, surprise – 0%!