Informer

One who snitches to the cops or feds/pheds, usually in exchange for leniency. Some plea bargains involve forcing a person to be an informer.
Also a song about informers by the white Reggae artist Snow, notorious for its incomprehensible lyrics.

In*form"er (?), n. [From Inform,v.]

1.

One who informs, animates, or inspires.

Thomson.

Nature, informer of the poet's art. Pope.

2.

One who informs, or imparts knowledge or news.

3. Law

One who informs a magistrate of violations of law; one who informs against another for violation of some law or penal statute.

Common informer Law, one who habitually gives information of the violation of penal statutes, with a view to a prosecution therefor. Bouvier. Wharton.

© Webster 1913.