1. Secret observation or gathering of information
   "The detective's spying led to the bust of a major drug ring"
    
2. The act of discovering or noticing something, especially by careful observation
   "His spying of the rare bird excited the whole group";
   - detection, catching, espial, spotting

1. Secretly collect sensitive or classified information; engage in espionage
   "spy for the Russians"
    
2. Watch, observe, or inquire secretly
   "The detective spied around the suspect's house for clues";
   - stag, snoop, sleuth
    
3. Catch sight of; to perceive with the eyes
   "We spyd a ship on the horizon";
   - sight, descry [literary], spot, espy

Derived forms: spyings

Type of: comprehend, discovery, enquire [Brit, Cdn], find, inquire, intelligence, intelligence activity, intelligence operation, investigate, monitor, perceive, supervise, uncovering, watchdog

Encyclopedia: Spying