🕵️ An informer 🪶 A decoy bird

stool pigeon

9.9

A fake bird used to attract or trap other birds

noun
/ˈstuːl ˈpɪdʒən/

Archaic

: pájaro señuelo

The hunters placed a stool pigeon near the trap to attract real birds.

Examples

Many birds were attracted to the stool pigeon decoy.
Using a stool pigeon helped them catch several doves during the hunt.
A wooden stool pigeon was positioned in the field as a lure.
The hunter placed a stool pigeon on the ledge.
The hunters placed a stool pigeon near the trap to attract real birds.
Using a stool pigeon helped them catch several doves during the hunt.
A wooden stool pigeon was positioned in the field as a lure.

Surface Forms

stool pigeon singular

stool pigeons plural

Morphology

stool + pigeon

The literal constituents ('stool' as a seat or obscurely a decoy and 'pigeon' as a bird) do not transparently yield the sense 'informer'; the idiomatic meaning comes from a historical practice of using a decoy bird and is not inferable from the parts by a typical B1 learner. Even if a learner knew a rare decoy-related sense of 'stool', the shift to ‘secret informant’ is culturally/historically specific and unpredictable.

Etymology

Stool pigeon comes from hunting. Hunters put a fake pigeon on a small seat or stake called a stool to lure real birds to a trap, so it meant a 'dummy pigeon' used as a decoy.