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]

The Collaborative International Dictionary of English v.0.48:

cutlass fish \cutlass fish\, cutlassfish \cutlassfish\n.
   1. (Zool.) a peculiar, long, thin, marine fish (Trichiurus
      lepturus) of the southern United States and West Indies,
      having a long whiplike scaleless body and sharp daggerlike
      teeth; -- called also frostfish, saber fish, silver
      eel, and, improperly, swordfish; also, several related
      members of the genus Trichiurus. It is closely related
      to snake mackerel.

   Syn: frost fish, frostfish, hairtail.
        [1913 Webster + WordNet 1.5]

WordNet (r) 3.0 (2006):

swordfish
    n 1: flesh of swordfish usually served as steaks
    2: 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]