The Collaborative International Dictionary of English v.0.48:

Swordfish \Sword"fish`\, n.
   1. (Zool.)
      (a) A very large oceanic fish (Xiphias gladius), the
          only representative of the family Xiphiidae. It is
          highly valued as a food fish. The bones of the upper
          jaw are consolidated, and form a long, rigid,
          swordlike beak; the dorsal fin is high and without
          distinct spines; the ventral fins are absent. The
          adult is destitute of teeth. It becomes sixteen feet
          or more long.
      (b) The gar pike.
      (c) The cutlass fish.
          [1913 Webster]

   2. (Astron.) A southern constellation. See Dorado, 1.
      [1913 Webster]

   Swordfish sucker (Zool.), a remora (Remora brachyptera)
      which attaches itself to the swordfish.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Xiphias gladius
    n 1: large toothless marine food fish with a long swordlike
         upper jaw; not completely cold-blooded i.e. they are able
         to warm their brains and eyes: worldwide in warm waters but
         feed on cold ocean floor coming to surface at night [syn:
         swordfish, Xiphias gladius]