1. (p. pr. & vb. n.) of Shadow.

2. (n.) Shade, or gradation of light and color; shading.

3. (n.) A faint representation; an adumbration.

ambuscade ambush ambushment blackening blind blocking the light booby trap bugging chase chasing cloak-and-dagger work clouding counterespionage counterintelligence darkening dimming dogging eclipsing electronic surveillance espial espionage extinguishment follow follow-up following heeling hounding hue and cry hunting intelligence intelligence work lurking hole military intelligence obfuscation obnubilation obscuration obscurement observation obumbration occulting overcast overclouding overshading overshadowing overshadowment prosecution pursual pursuance pursuing pursuit quest searching secret police secret service seeking sequel sequence series shading spying stakeout stalking stalking-horse surveillance tailing tracking tracking down trailing trap wiretap wiretapping