stool pigeon

noun

1. a pigeon used as a decoy.

2. Also called stooly. Also called stoolie. Slang.,  a person employed or acting as a decoy or informer, especially for the police.

stool pigeon

noun

1. a living or dummy pigeon used to decoy others

2. an informer for the police; nark

3. slang,  a person acting as a decoy

stool pigeon

1. An informer, especially for the police: “Lefty figured out that Mugsy was the stool pigeon when he saw him talking to the warden.”

Word History and Origins

Origin of stool pigeon¹

An Americanism dating back to 1820–30

Idioms and Phrases

A decoy or informer, especially a police spy. For example, Watch out for Doug; I'm sure he's a stool pigeon for the supervisor. This term alludes to a bird tied to a stool or similar perch in order to attract other birds, which will then be shot. However, one writer believes that stool is a variant for stale or stall, both nouns used for a decoy bird before 1500 or so. [c. 1820]