- the act or practice of spying.
- the use of spies by a government to discover the military and political secrets of other nations.
- the use of spies by a corporation or the like to acquire the plans, technical knowledge, etc., of a competitor: industrial espionage.
- the systematic use of spies to obtain secret information, esp by governments to discover military or political secrets
- the act or practice of spying
1793, from French espionnage “spying,” from Middle French espionner “to spy,” from Old French espion “spy,” probably via Italian spione from a Germanic source akin to Old High German spehon “spy” (see spy).