The Collaborative International Dictionary of English v.0.48:

Longshoreman \Long"shore`man\, n.; pl. Longshoremen. [Abbrev.
   fr. alongshoreman.]
   One of a class of laborers employed about the wharves of a
   seaport, especially in loading and unloading vessels.
   [1913 Webster]

WordNet (r) 3.0 (2006):

longshoreman
    n 1: a laborer who loads and unloads vessels in a port [syn:
         stevedore, loader, longshoreman, docker,
         dockhand, dock worker, dockworker, dock-walloper,
         lumper]