Wordnet 3.0
NOUN (1)
1.
intelligence activities concerned with identifying and counteracting the threat to security posed by hostile intelligence organizations or by individuals engaged in espionage or sabotage or subversion or terrorism;
WordNet (r) 3.0 (2006):
counterintelligence
n 1: intelligence activities concerned with identifying and
counteracting the threat to security posed by hostile
intelligence organizations or by individuals engaged in
espionage or sabotage or subversion or terrorism
Moby Thesaurus II by Grady Ward, 1.0:
24 Moby Thesaurus words for "counterintelligence":
bugging, cloak-and-dagger work, counterespionage,
electronic surveillance, espial, espionage, following,
intelligence, intelligence bureau, intelligence service,
intelligence work, military intelligence, naval intelligence,
observation, secret police, secret service, shadowing, spying,
stakeout, surveillance, tailing, trailing, wiretap, wiretapping