Espionage \Es"pi*o*nage\ (?; 277), n. [F. espionnage, fr. espionner to spy, fr. espion spy, OF. espie. See Espy.]

The practice or employment of spies; the practice of watching the words and conduct of others, to make discoveries, as spies or secret emissaries; secret watching.

Source: Webster's Revised Unabridged Dictionary (1913)