confederate
Definitions
A person, group, or nation united with others for a common purpose, especially in a conspiracy.
Joined by an agreement or treaty; allied.
An accomplice in a crime or secret plot.
Examples
The thief was caught after his confederate accidentally triggered the silent alarm.
The two nations decided to confederate in order to strengthen their economic ties against global competition.
Synonyms
ally accomplice associate partner colleague cohort collaborator