What is the Meaning of the Phrase ‘Foam at the Mouth’?

And where did it come from?

The expression “Foam at the mouth” or “Froth at the mouth” can mean two things, both of which are related and derived from the same source —

• To be diseased with some ailment
• To be in a state of uncontrolled anger

Many animals such as horses produce a mass of bubbles in and around their mouth when they are very ill or angry. Dogs, when they are afflicted with rabies, literally foam at their mouth. They produce abundant froth and behave crazily in an uncontrolled manner.

Thus, when we use this expression for an animal, it is usually to say that the animal is diseased or ill. But when we use this expression for a person, it is to indicate that the person is in a state of rage, the person is furious.

For example —

“He foamed at the mouth when he saw that his new car was badly scratched on the side”.

It means that he was furious, he was in an uncontrolled rage when he saw his new car badly scratched.

I hope you found this story interesting. If you did, buy my full course on Udemy or watch it for free on Skillshare by signing up here. This course covers nearly 380 idioms with their origins and backstories.

Hi, I am Gauri Shanker, a Vocab teacher and enthusiast. I teach vocabulary in a fun and engaging way. You can check out my courses here.