Main entry: spy, undercover agent
Definition: (military) a secret agent hired by a state to obtain information about its enemies or by a business to obtain industrial secrets from competitors
Main entry: spy
Definition: a secret watcher; someone who secretly watches other people
Usage: my spies tell me that you had a good time last night
Main entry: spy
Definition: secretly collect sensitive or classified information; engage in espionage
Usage: spy for the Russians
Main entry: spy, stag, sleuth, snoop
Definition: watch, observe, or inquire secretly
Main entry: descry, spot, spy, espy
Definition: catch sight of
Definition: catch sight of; to perceive with the eyes
Usage: he caught sight of the king's men coming over the ridge