The Collaborative International Dictionary of English v.0.48:

Trolley \Trol"ley\, Trolly \Trol"ly\, n.
   (a) A form of truck which can be tilted, for carrying
       railroad materials, or the like. [Eng.]
   (b) A narrow cart that is pushed by hand or drawn by an
       animal. [Eng.]
   (c) (Mach.) A truck from which the load is suspended in some
       kinds of cranes.
   (d) (Electric Railway) A truck which travels along the fixed
       conductors, and forms a means of connection between them
       and a railway car.
   (e) A trolley car.
       [1913 Webster]

WordNet (r) 3.0 (2006):

trolley
    n 1: a wheeled vehicle that runs on rails and is propelled by
         electricity [syn: streetcar, tram, tramcar,
         trolley, trolley car]