spy

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

Synonyms: case catch sight of discover examine eyeball fish out get a load of glimpse keep under surveillance look for meddle notice observe peep pry recon reconnoiter scout scrutinize search set eyes on shadow sleuth snoop spot stag stake out tail take in take note trail view watch