In his stupid book How The Irish Invented Slang, Daniel Cassidy claims that the English word grumble comes from the Irish gruaim béal or gruaim béil, meaning despondency of mouth. As usual, the Irish phrase which is supposedly the origin of the word is not a real Irish phrase and Cassidy provides no evidence for its use. Try looking it up on Google. And it really isn’t a likely expression anyway.
Think about it. People complain a lot and because of that, all cultures have basic words for the activity. They don’t need to put words together into phrases to express the concept. They use grouch, or kvetch, or gearán. A single word is enough to express it.
A foreigner speaking a pidgin version of Irish might need to talk about their despondency of mouth. A native Irish speaker wouldn’t need to, because they would have single words to express the concept of grumble or complaint. In other words, simple logic should tell you this is unlikely.
As usual, Cassidy lied about the source of the word. He says that the OED says ‘proximate source uncertain.’ This is very telling. Proximate source. Proximate means immediate. Here’s what the OED really has to say on this subject, before the Great Fraud cut it and twisted it into the shape that suited him:
“Etymology: Proximate source uncertain: compare French grommeler to mutter between the teeth, Dutch grommelen, < grommen to rumble, growl (compare GRUMME, v.), German grummeln to rumble.”
In other words, grumble is closely related in sound and meaning to words in German and Dutch, as well as a Germanic loanword in French. It’s either a borrowing from German or Dutch or an unrecorded cognate of these words in Old English. The details of this are in doubt, hence the ‘proximate source uncertain’. The Germanic origin isn’t. The wind doesn’t blow from the south and the north at the same time. If the word comes from the Germanic languages, it doesn’t come from Irish, even if the supposed Irish derivation were really convincing, which in this case it isn’t.
More lies, more nonsense, more garbage.