Foaming at the mouth is an idiom that has been in use for hundreds of years. An idiom is a commonly used word, group of words, or phrase that has a figurative meaning that is not easily deduced from its literal definition. Often using descriptive imagery or metaphors, common idioms are words and phrases used in the English language in order to convey a concise idea, and are often spoken or are considered informal or conversational. English idioms can illustrate emotion more quickly than a phrase that has a literal meaning, even when the etymology or origin of the idiomatic expression is lost. An idiom is a metaphorical figure of speech, and it is understood that it is not a use of literal language. Figures of speech like an often-used metaphor have definitions and connotations that go beyond the literal meaning of the words. Mastery of the turn of phrase of an idiom, which may use slang words or other parts of speech common in American slang or British slang, is essential for the English learner. Many English as a Second Language students do not understand idiomatic expressions and idiomatic language such as hit the sack, spill the beans, let the cat out of the bag, silver lining, back to the drawing board, barking up the wrong tree, kick the bucket, hit the nail on the head, face the music, under the weather, piece of cake, when pigs fly, and raining cats and dogs, because they attempt to translate them word for word, which yields only the literal meaning. English phrases that are idioms should not be taken literally. In addition to learning vocabulary and grammar, one must understand the phrasing of the figurative language of idiomatic phrases in order to know English like a native speaker; it is helpful to maintain a list of phrases, common expressions, colloquial terms, and popular expressions to memorize that are used figuratively or idiomatically. We will examine the meaning of the common idiom foaming at the mouth where it came from, and some examples of its idiomatic usage in sentences.
Foaming at the mouth describes being in a rage or being very angry. The phrase foaming at the mouth has been in use for quite awhile in a literal sense; it is a symptom of rabies. Rabies is a virus that is fatal if untreated, and often fatal even if treated. The symptoms of rabies include aggression, bizarre behavior, hallucinations, muscle spasms, etc. One of the symptoms of rabies is foaming at the mouth, because the victim cannot swallow properly. Therefore, foaming at the mouth is equated with rage. It is unclear exactly when the expression foaming at the mouth became a idiom, though it has been one for at least several hundred years. Related phrases are foam at the mouth, foams at the mouth, foamed at the mouth.
He was shouting and foaming at the mouth. (Manchester Evening News)
Schallenberg added that “it won’t be possible to solve the Middle East conflict while foaming at the mouth.” (AP News)
So we met the next day and of course I was foaming at the mouth with this laundry list of things I wanted to do — outdoor festivals and markets and fairs and concerts and private events. (Lexington Herald Leader)