The Collaborative International Dictionary of English v.0.48:

Canis \Ca"nis\ (k[a^]"n[i^]s), n.; pl. Canes (-n[=e]z). [L., a
   dog.] (Zool.)
   A genus of carnivorous mammals, of the family Canid[ae],
   including the dogs and wolves.
   [1913 Webster]

   Canis major [L., larger dog], a constellation to the
      southeast of Orion, containing Sirius or the Dog Star.

   Canis minor [L., smaller dog], a constellation to the east
      of Orion, containing Procyon, a star of the first
      magnitude.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Canis Major
    n 1: a constellation to the southeast of Orion; contains Sirius
         [syn: Canis Major, Great Dog]