The Collaborative International Dictionary of English v.0.48:

Frostfish \Frost`fish"\, n. (Zool.)
      (a) The tomcod; -- so called because it is abundant on the
          New England coast in autumn at about the commencement
          of frost. See Tomcod.
      (b) The smelt. [Local, U. S.]
      (c) A name applied in New Zealand to the scabbard fish
          (Lepidotus) valued as a food fish.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Scabbard \Scab"bard\, n. [OE. scaubert, scauberk, OF. escaubers,
   escauberz, pl., scabbards, probably of German or Scan.
   origin; cf. Icel. sk[=a]lpr scabbard, and G. bergen to
   conceal. Cf. Hauberk.]
   The case in which the blade of a sword, dagger, etc., is
   kept; a sheath.
   [1913 Webster]

         Nor in thy scabbard sheathe that famous blade.
                                                  --Fairfax.
   [1913 Webster]

   Scabbard fish (Zool.), a long, compressed, silver-colored
      taenioid fish (Lepidopus argyreus syn. Lepidopus
      caudatus), found on the European coasts, and more
      abundantly about New Zealand, where it is called
      frostfish and considered an excellent food fish.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Tomcod \Tom"cod`\ (t[o^]m"k[o^]d`), n. [Tom (see Tomboy) +
   cod: cf. F. tacaud whiting pout, American Indian tacaud,
   literally, plenty fish.] (Zool.)
   (a) A small edible American fish (Microgadus tomcod) of the
       Codfish family, very abundant in autumn on the Atlantic
       coast of the Northen United States; -- called also
       frostfish. See Illust. under Frostfish.
   (b) The kingfish. See Kingfish
   (a) .
   (c) The jack. See 2d Jack, 8.
   (c) .
       [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]