cheese eater

American  

noun

Slang.

1. an informer; rat.

2. a person who betrays, denies, or abandons their associates, social group, beliefs, etc.

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Etymology

Origin of cheese eater

An Americanism dating back to 1870–75; the sense “informer”; in association of cheese with rat

Example Sentences

“But Buchalter was no cheese eater and wouldn’t squeal. On March 5, 1944, he went like a mensch to ‘Old Sparkie’ in Sing Sing.”

From New York Times

That’s roughly your situation as a cheese eater in America, where the cheeses we eat are all pasteurized, an unnecessary treatment that kills flavor along with germs.

From Time

A "cheese eater" is an informant.

From The Wall Street Journal

Cheese The Cypriot is a great cheese eater.

From Project Gutenberg