[spahy] 
,noun, plural spies, verb, spied, spy⋅ing.| 1. | a person employed by a government to obtain secret information or intelligence about another, usually hostile, country, esp. with reference to military or naval affairs. |
| 2. | a person who keeps close and secret watch on the actions and words of another or others. |
| 3. | a person who seeks to obtain confidential information about the activities, plans, methods, etc., of an organization or person, esp. one who is employed for this purpose by a competitor: an industrial spy. |
| 4. | the act of spying. |
| 5. | to observe secretively or furtively with hostile intent (often fol. by on or upon). |
| 6. | to act as a spy; engage in espionage. |
| 7. | to be on the lookout; keep watch. |
| 8. | to search for or examine something closely or carefully. |
| 9. | to catch sight of suddenly; espy; descry: to spy a rare bird overhead. |
| 10. | to discover or find out by observation or scrutiny (often fol. by out). |
| 11. | to observe (a person, place, enemy, etc.) secretively or furtively with hostile intent. |
| 12. | to inspect or examine or to search or look for closely or carefully. |
spy on
Secretly or furtively observe someone or something, as in The children loved spying on the grownups, or The company sent him to spy on the competitor's sales force. [Early 1600s]