sneaker

from WordNet (r) 3.0 (2006)

sneaker
    n 1: a canvas shoe with a pliable rubber sole [syn: {gym shoe},
         {sneaker}, {tennis shoe}]
    2: someone acting as an informer or decoy for the police [syn:
       {fink}, {snitch}, {snitcher}, {stoolpigeon}, {stool pigeon},
       {stoolie}, {sneak}, {sneaker}, {canary}]

from The Collaborative International Dictionary of English v.0.48

Sneaker \Sneak"er\ (sn[=e]k"[~e]r), n.
   1. One who sneaks. --Lamb.
      [1913 Webster]

   2. A vessel of drink. [Prov. Eng.]
      [1913 Webster]

            A sneaker of five gallons.            --Spectator.
      [1913 Webster]

   3. A type of soft shoe with a flat, pliable, typically rubber
      or other soft sole, and canvas-like upper, used in sports
      such as tennis, or for comfort. Called sneaker because
      they give no warning of one's approach. Usually used in
      the pl.
      [Webster 1913 Suppl. +PJC]

   4. A punch bowl. [Obs.] --Spectator.
      [Webster 1913 Suppl.]

from Jargon File (4.4.4, 14 Aug 2003)

sneaker
 n.

   An individual hired to break into places in order to test their
   security; analogous to {tiger team}. Compare {samurai}.