| Main Entry: | |
| Part of Speech: | noun |
| Definition: | person who secretly finds out about another's business |
| Synonyms: | agent, detective, double agent, emissary, espionage agent, foreign agent, informer, inside agent, intelligencer, investigator, lookout, mole, observer, operative, patrol, picket, plant*, scout, secret agent, secret service, sleeper, sleuth, snoop, spook, spotter, undercover agent, watcher |