spy

Nouns

• (n) (military) a secret agent hired by a state to obtain information about its enemies or by a business to obtain industrial secrets from competitors undercover agent,
• (n) a secret watcher; someone who secretly watches other people
  • my spies tell me that you had a good time last night

Verbs

• (v) catch sight of descry, espy, spot,
• (v) watch, observe, or inquire secretly sleuth, snoop, stag,
• (v) catch sight of; to perceive with the eyes
  • he caught sight of the king's men coming over the ridge
  sight,
• (v) secretly collect sensitive or classified information; engage in espionage
  • spy for the Russians

Synonyms

Words of close approximity