double agent

noun
1.
a person who spies on a country while pretending to spy for it.
2.
a spy in the service of two rival countries, companies, etc.
Origin
1930-35
Examples from the web for double agent
  • There were rumors there might be a third double agent.
  • Sparkling in his role as a conscience-struck double agent, he fights intrigue and physical danger to triumph in the end.
British Dictionary definitions for double agent

double agent

noun
1.
a spy employed by two mutually antagonistic countries, companies, etc
Word Origin and History for double agent
n.

1935, from double (adj.) + agent (n.).