''Foam''
I understand that the english word ''foam'' can be used as either a noun or a verb. In the first case, it gets the meaning of ''a mass of small bubbles on the surface of a liquid, etc. (e.g.: ''The water curved round the rocks in bursts of foam''); whereas in the second case, it means ''to produce or emit foam'', as in '' The beer foamed in the glass.''

However, I happened to find another different meaning for this word, which is ''to be extremely angry'' or ''to rage'', as in the phrase ''He was foaming over the disastrous budget cuts.'' Therefore, I would like to know whether this meaning is truly accepted or not. If so, could you tell me if such usage is that of a formal speech or an informal one?

Thank you very much.

Question

''Foam''
I understand that the english word ''foam'' can be used as either a noun or a verb. In the first case, it gets the meaning of ''a mass of small bubbles on the surface of a liquid, etc. (e.g.: ''The water curved round the rocks in bursts of foam''); whereas in the second case, it means ''to produce or emit foam'', as in '' The beer foamed in the glass.''

However, I happened to find another different meaning for this word, which is ''to be extremely angry'' or ''to rage'', as in the phrase ''He was foaming over the disastrous budget cuts.'' Therefore, I would like to know whether this meaning is truly accepted or not. If so, could you tell me if such usage is that of a formal speech or an informal one?

Thank you very much.

Answer

Yes, this is an accepted meaning, probably, as Chris suggests, from "foaming at the mouth".  Longmans has it too https://www.ldoceonline.com/dictionary/foam

Answer

I agree with Flo, I hear "fuming" more often than "foaming" when describing someone is mad.

Answer

I haven't heard that expression used before. However, I have heard (fuming over) before.

He was fuming over his broken ps4

Dogs foam at the mouth, for various reasons, including stress.

Answer

another version could be a misprint or mistyping of "foaming at the mouth" which is also an   expression for being angry, like some animals, dogs, bulls, rabid dogs and several creatures give this warning sign of being ready to attack.

Answer

This is a reference to rabid dogs foaming at the mouth.  Your sentence is a shortened version of "[He was so angry that] He was foaming [at the mouth] over the disastrous budget cuts."  I consider it informal.

Both the online Oxford Learner's Dictionaries and the online Collins Dictionary include it.

Oxford Learner's Dictionaries
https://www.oxfordlearnersdictionaries.com/definition/english/foam_2#foam_idmg_1

Collins Dictionary
https://www.collinsdictionary.com/dictionary/english/foam