WordNet (r) 3.0 (2006):

hijacking
    n 1: robbery of a traveller or vehicle in transit or seizing
         control of a vehicle by the use of force [syn:
         highjacking, hijacking]

Moby Thesaurus II by Grady Ward, 1.0:

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