Stool pigeon and Tipster

Stool pigeon noun - A person who provides information about another's wrongdoing.

Tipster and stool pigeon are semantically related in knowledge topic. In some cases you can use "Tipster" instead a noun phrase "Stool pigeon", when it comes to topics like informer to police.

Tipster noun - One who sells advice about gambling or speculation (especially at the racetrack).

Stool pigeon and tipster are semantically related in knowledge topic. You can use "Stool pigeon" instead a noun "Tipster", if it concerns topics such as sneak, gossip, informer, reporter.