Tradecraft

Definition
Tradecraft is the techniques adopted by spies to conceal their activities. They include: assessment; cover and disguise; concealments; clandestine surveillance; and covert communications.

Source

 * Office of Counterintelligence (DXC), Defense CI & HUMINT Center, Defense Intelligence Agency, "Terms and Definitions of Interest for DoD Counterintelligence Professional," at GL-174 (May 2, 2011) (full-text).