canary

(noun) someone acting as an informer or decoy for the police. Synonyms: fink, snitch, snitcher, stoolpigeon, stool pigeon, stoolie, sneak, sneaker.

(noun) a female singer.

(noun) a moderate yellow with a greenish tinge. Synonyms: canary yellow.

(noun) any of several small Old World finches. Synonyms: canary bird.

(adj) having the color of a canary; of a light to moderate yellow. Synonyms: canary-yellow.