The Collaborative International Dictionary of English v.0.48:

Fireman \Fire"man\, n.; pl. Firemen (-men).
   1. A man whose business is to extinguish fires in towns; a
      member of a fire company.
      [1913 Webster]

   2. A man who tends the fires, as of a steam engine; a
      stocker.
      [1913 Webster]

WordNet (r) 3.0 (2006):

fireman
    n 1: play in which children pretend to put out a fire
    2: a laborer who tends fires (as on a coal-fired train or
       steamship) [syn: stoker, fireman]
    3: a pitcher who does not start the game [syn: reliever,
       relief pitcher, fireman]
    4: a member of a fire department who tries to extinguish fires
       [syn: fireman, firefighter, fire fighter, fire-eater]

Moby Thesaurus II by Grady Ward, 1.0:

62 Moby Thesaurus words for "fireman":
   baggage man, bakehead, black gang, boilerman, brakeman, brakie,
   bungs, butcher, cabin boy, chips, commissary steward, complement,
   conductor, deckhand, deckie, dispatcher, fire brigade,
   fire department, fire fighter, fire warden, fire-chaser,
   fire-eater, footplate man, forest fire fighter, guard, gun loader,
   gunner, hand, hospital steward, landing signalman, lineman,
   mail orderly, navigator, oiler, porter, purser, radio operator,
   railroad man, railroader, redcap, roustabout, smoke agent,
   smokechaser, smokejumper, snip, snips, sparks, stationmaster,
   steward, stewardess, stoker, switchman, torpedoman, trainboy,
   trainman, trainmaster, vamp, volunteer fireman, watch, yardman,
   yardmaster, yeoman