WordNet (r) 3.0 (2006):

stickup
    n 1: robbery at gunpoint [syn: armed robbery, heist,
         holdup, stickup]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "stickup":
   armed robbery, asportation, assault and robbery, banditry,
   bank robbery, cattle lifting, cattle stealing, extortion, heist,
   highway robbery, hijacking, holdup, mugging, pocket picking,
   purse snatching, robbery, robbing, stickup job