Source : Webster's Revised Unabridged Dictionary (1913)

Hail \Hail\, interj. [See {Hail}, v. t.]
   An exclamation of respectful or reverent salutation, or,
   occasionally, of familiar greeting. ``Hail, brave friend.''
   --Shak.

   {All hail}. See in the Vocabulary.

   {Hail Mary}, a form of prayer made use of in the Roman
      Catholic Church in invocation of the Virgin. See {Ave
      Maria}.

Source : WordNet®

Hail Mary
     n : a salutation to the Virgin Mary now used in prayers to Her
         [syn: {Ave Maria}]