Spy  —n. (pl. Spies) 1 person who secretly collects and reports information for a government, company, etc. 2 person watching others secretly. —v. (spies, spied) 1 discern, see. 2 (often foll. By on) act as a spy. 3 (often foll. By into) pry.  spy out explore or discover, esp. Secretly. [french espie, espier]