shadowing (n.)
- ambuscade
- ambush
- blackening
- blind
- chase
- chasing
- clouding
- counterespionage
- counterintelligence
- darkening
- espial
- espionage
- follow-up
- following
- heeling
- hunting
- intelligence
- obfuscation
- observation
- overcast
- prosecution
- pursual
- pursuance
- pursuit
- quest
- searching
- seeking
- sequel
- sequence
- series
- shading
- spying
- stakeout
- stalking
- stalking-horse
- surveillance
- tailing
- tracking
- trailing
- trap
- wiretap
