Definition of "stooge"

One who knowingly allows himself or herself to be used for another's profit; a dupe.  examples

(magic) A magician's assistant who pretends to be a member of the audience.  examples

(comedy) A straight man.  examples

A secret informant for police.  examples

(psychology) A confederate; a person who is secretly working for the researcher, unknown to the study participant.

(intransitive) To act as a straight man.  examples