The Collaborative International Dictionary of English v.0.48:

Calliope \Cal*li"o*pe\ (k[a^]l*l[imac]"[-o]*p[-e]), n. [L.
   Calliope, Gr. Kallio`ph, lit, the beautiful-voiced; pref.
   kalli- (from kalo`s beautiful) + 'o`ps, 'opo`s, voice.]
   1. (Class. Myth.) The Muse that presides over eloquence and
      heroic poetry; mother of Orpheus, and chief of the nine
      Muses.
      [1913 Webster]

   2. (Astron.) One of the asteroids. See Solar.
      [1913 Webster]

   3. A musical instrument consisting of a series of steam
      whistles, toned to the notes of the scale, and played by
      keys arranged like those of an organ. It is sometimes
      attached to steamboat boilers.
      [1913 Webster]

   4. (Zool.) A beautiful species of humming bird (Stellula
      Calliope) of California and adjacent regions.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Calliope
    n 1: (Greek mythology) the Muse of epic poetry
    2: a musical instrument consisting of a series of steam whistles
       played from a keyboard [syn: calliope, steam organ]