(military) a secret agent hired by a state to obtain information about its enemies or by a business to obtain industrial secrets from competitors
- She worked as an undercover agent for the police.
- An agent provocateur reported that the enemy had started out.
- Aha, the agent thought, here's my man.
- We soon found out that he was a secret agent.
- That store was a front for foreign agent.
- Again some believed that he was a Tsarist agent.
- under cover 秘密地