Synonyms: fifth columnist, saboteur
Definition: a member of a clandestine subversive organization who tries to help a potential invader
Similar words: traitor, treasonist
Definition: someone who betrays his country by committing treason
Synonyms: saboteur, wrecker, diversionist
Definition: someone who commits sabotage or deliberately causes wrecks
Similar words: destroyer, uprooter, waster, undoer, ruiner
Definition: a person who destroys or ruins or lays waste to
Usage: a destroyer of the environment; jealousy was his undoer; uprooters of gravestones