Spy

1. To explore; to view; inspect; and examine secretly, as a country; -- usually with out.
2. One who keeps a constant watch of the conduct of others.
3. To search narrowly; to scrutinize.
4. To gain sight of; to discover at a distance, or in a state of concealment; to espy; to see.
5. To discover by close search or examination.
6. A person sent secretly into an enemy's camp, territory, or fortifications, to inspect his works, ascertain his strength, movements, or designs, and to communicate such intelligence to the proper officer.