undercover_agent
1. [ noun ] (military) a secret agent hired by a state to obtain (military) information about its enemies or by a business to obtain industrial secrets from competitors
Synonyms: spy
Related terms: secret_agent espionage_agent Mata_Hari foreign_agent counterspy infiltrator double_agent sleeper military
Similar spelling:   undercover_work
  undercarriage
  underperformer
  under_your_nose