1
investigate
1
keep under surveillance(verb, expression, idiom, examine, case)
1
look for(verb, expression, examine, case, discover)
1
lookout(noun, plant, watch, guard, agent)
1
meddle(verb, examine, case, discover, watch)
1
messenger
1
mole(noun, plant, watch, agent, spy)
1
narc
1
nark(agent, spy, informer, reporter, gumshoe)
1
newsmonger
1
notice(noun, verb, examine, discover, watch)
1
observe(verb, examine, discover, watch, scrutinize)
1
observer(noun, plant, agent, spy, operative)
1
patrol(noun, plant, watch, guard, agent)
1
peach
1
peep(verb, examine, discover, watch, scrutinize)
1
peeper(noun, agent, spy, informer, reporter)
1
picket(noun, plant, watch, guard, agent)
1
plainclothes officer(expression, agent, spy, hound, informer)
1
plainclothesman
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APASmart Define. (2015). sleuth thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/sleuth/thesaurus/synonyms
ChicagoSmart Define. 2015. "sleuth thesaurus" https://smartdefine.org/sleuth/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2015, sleuth thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/sleuth/thesaurus/synonyms>.
MLASmart Define. "sleuth thesaurus" 14 April 2015. Web. 22 September 2026. <https://smartdefine.org/sleuth/thesaurus/synonyms>