The Collaborative International Dictionary of English v.0.48:

Ormazd \Or"mazd\, Ormuzd \Or"muzd\ or Ahura-Mazda
\A`hu*ra-Maz"da\, n. [Zend Ahuramazda.] (Zoroastrianism)
   The supreme deity, the embodiment of the principle of good,
   creator of the world, source of light, and guardian of
   mankind. He is the opponent of Ahriman, the spirit of evil,
   both being sprung from Eternity, or, according to another
   version, Ahriman being the offspring of a moment of doubt on
   the part of Ormazd. Ormazd is attended by angels and
   archangels. He is represented as a bearded man inclosed in a
   winged circle, a conception probably derived from the
   Assyrian representations of Ashur.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

Ormazd
    n 1: chief deity of Zoroastrianism; source of light and
         embodiment of good [syn: Ormazd, Ormuzd, Ahura Mazda]