The Collaborative International Dictionary of English v.0.48:

Grampus \Gram"pus\, n.; pl. Grampuses. [Probably corrupted
   from It. gran pesce great fish, or Sp. gran pez, or Pg. gran
   peixe, all fr. L. grandis piscis. See Grand, and Fish.
   the animal.]
   1. (Zool.) A toothed delphinoid cetacean, of the genus
      Grampus, esp. G. griseus of Europe and America, which
      is valued for its oil. It grows to be fifteen to twenty
      feet long; its color is gray with white streaks. Called
      also cowfish. The California grampus is G. Stearnsii.
      [1913 Webster]

   2. A kind of tongs used in a bloomery. [U.S.] Granade

The Collaborative International Dictionary of English v.0.48:

orc \orc\ ([^o]rk), n. [L. orca, a kind of whale: cf. F. orque.]
   1. (Zool.) Any of several cetaceans, especialy the grampus
      (Grampus griseus) of the dolphin family. [Written also
      ork and orch.] --Milton.
      [1913 Webster]

            An island salt and bare,
            The haunt of seals, and orcs, and sea-mews' clang.
                                                  --Milton (Par.
                                                  Lost xi. 835).

   2. (Mythology) A mythical monster of varying descriptions; an
      ogre.
      [PJC]

            Goblins, hobgoblins, and orcs of the worst
            description.                          --J. J.
                                                  Tolkien (The
                                                  Hobbit)

   3. The orca.
      [PJC]

WordNet (r) 3.0 (2006):

grampus
    n 1: predatory black-and-white toothed whale with large dorsal
         fin; common in cold seas [syn: killer whale, killer,
         orca, grampus, sea wolf, Orcinus orca]
    2: slaty-grey blunt-nosed dolphin common in northern seas [syn:
       grampus, Grampus griseus]