gumshoe
[noun]
Synonyms: detective, dick, eye, hawkshaw, investigator, plainclothesman, Sherlock, Sherlock Holmes, sleuth, tec, policeman, bull, cop, flatfoot, fuzz, heat, officer, peeler, pig, police officer
[verb]
Synonyms: sneak, creep, lurk, pussyfoot, shirk, skulk, slink, slip, snake, steal

[TahlilGaran] English Synonym Dictionary ▲

gum‧shoe /ˈɡʌmʃuː/ noun [countable] American English old-fashioned
[Date: 1900-2000; Origin: gumshoe 'rubber shoe' (19-20 centuries); because detectives walk quietly]
a detective

[TahlilGaran] Dictionary of Contemporary English ▲