The Collaborative International Dictionary of English v.0.48:

Orion \O*ri"on\ ([-o]*r[imac]"[o^]n), n. [L., fr. Gr. 'Wri`wn,
   orig., a celebrated hunter in the oldest Greek mythology,
   after whom this constellation was named.] (Astron.)
   A large and bright constellation on the equator, between the
   stars Aldebaran and Sirius. It contains a remarkable nebula
   visible to the naked eye.
   [1913 Webster]

         The flaming glories of Orion's belt.     --E. Everett.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Orion
    n 1: (Greek mythology) a giant Boeotian hunter who pursued the
         Pleiades and was eventually slain by Artemis; was then
         placed in the sky as a constellation
    2: a constellation on the equator to the east of Taurus;
       contains Betelgeuse and Rigel [syn: Orion, Hunter]