The Collaborative International Dictionary of English v.0.48:

Hail \Hail\, interj. [See Hail, v. t.]
   An exclamation of respectful or reverent salutation, or,
   occasionally, of familiar greeting. "Hail, brave friend."
   --Shak.
   [1913 Webster]

   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.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Hail Mary
    n 1: a salutation to the Virgin Mary now used in prayers to her
         [syn: Ave Maria, Hail Mary]

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "Hail Mary":
   Angelus, Ave, Ave Maria, Kyrie Eleison, Paternoster, aid prayer,
   appeal, beadroll, beads, beseechment, bidding prayer, breviary,
   chaplet, collect, communion, contemplation, devotions, entreaty,
   grace, impetration, imploration, intercession, invocation, litany,
   meditation, obsecration, obtestation, orison, petition, prayer,
   prayer wheel, rogation, rosary, silent prayer, suit, supplication,
   thanks, thanksgiving