i. casus, ajan. There is a spy among us. (Aramızda bir casus var.)

To discover by close search or examination.

To explore; to view; inspect; and examine secretly, as a
country; – usually with out.

To search narrowly; to scrutinize.

One who keeps a constant watch of the conduct of others.

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.