The Collaborative International Dictionary of English v.0.48:

Bombardier \Bom`bar*dier"\, n. [F. bombardier.] (Mil.)
   (a) One who used or managed a bombard; an artilleryman; a
       gunner. [Archaic]
   (b) A noncommissioned officer in the British artillery.
       [1913 Webster]

   Bombardier beetle (Zool.), a kind of beetle (Brachinus
      crepitans), so called because, when disturbed, it makes
      an explosive discharge of a pungent and acrid vapor from
      its anal glands. The name is applied to other related
      species, as the Brachinus displosor, which can produce
      ten or twelve explosions successively. The common American
      species is Brachinus fumans.
      [1913 Webster]

WordNet (r) 3.0 (2006):

bombardier
    n 1: a noncommissioned officer in the British artillery
    2: the member of a bomber crew responsible for using the
       bombsight and releasing the bombs on the target

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "bombardier":
   aerial photographer, aircrew, aircrewman, artillerist,
   artilleryman, avigator, belly gunner, bomb thrower, bomber,
   cannoneer, crew, crew chief, flight attendant, flight crew, gunner,
   hostess, machine gunner, meteorologist, navigator, steward,
   stewardess