Canary-yellow adjective – Having the color of a canary; of a light to moderate yellow. Stoolpigeon and canary-yellow are semantically related. In some cases you can use "Stoolpigeon" instead a noun phrase "Canary-yellow".
Stoolpigeon noun – Someone acting as an informer or decoy for the police. Canary-yellow and stoolpigeon are semantically related. Sometimes you can replace phrase "Canary-yellow" with "Stoolpigeon", this terms are similar.