From Longman Dictionary of Contemporary Englishgumshoegum‧shoe /ˈɡʌmʃuː/ noun [countable] American English old-fashioned INVESTIGATEa detective
Examples from the Corpus
gumshoe• Dennis Miller is a down-at-the-heels gumshoe.• But he makes the pulp gumshoe formula look like a comforting ritual only normal societies can perform.• With Petersen under lock and key, life for the gumshoes of the Office of Security returned to normal.Origin gumshoe (1900-2000) gumshoe “rubber shoe” ((19-20 centuries)); because detectives walk quietly 