1. (espionage) snitch, grass, tell-tale (police informant) (informal)

2. mouchard (undercover investigator) (espionage)

3. bug (hidden microphone) (espionage)

4. spyhole, peephole (espionage)

5. tachograph (device that records the distance and time traveled by a vehicle)

6. (computing) spyware (piece of spyware) (espionage)

7. (aviation) spyplane (espionage)

8. black box, flight recorder (aviation)