gumshoe (GUM-shoo) noun
1. A detective.
2. A rubber overshoe.
[The word is an allusion to the quiet snooping that a detective is supposed to do. Wearing rubber shoes, one can move around without making much noise.]
The word is an example of the figure of speech called synecdoche, in which a part is used for the whole or vice versa. Other examples are the use of the word crown to refer to a king or a hand to refer to a farm worker.
Today's word in Visual Thesaurus.
"So far, the entertainment industry's approach to peer-to-peer file sharing has been to hire gumshoes to bang on teenagers' doors at midnight and haul them off to court -- an act akin to trying to beat back a tsunami with a tennis racquet."
-- Staunching a Tide of Piracy; Sydney Morning Herald (Australia); May 18, 2006.