The Collaborative International Dictionary of English v.0.48:

Beatitude \Be*at"i*tude\, n. [L. beatitudo: cf. F. b['e]atitude.
   See Beatify.]
   1. Felicity of the highest kind; consummate bliss.
      [1913 Webster]

   2. Any one of the nine declarations (called the Beatitudes),
      made in the Sermon on the Mount (--Matt. v. 3-12), with
      regard to the blessedness of those who are distinguished
      by certain specified virtues.
      [1913 Webster]

   3. (R. C. Ch.) Beatification. --Milman.
      [1913 Webster]

   Syn: Blessedness; felicity; happiness.
        [1913 Webster]

WordNet (r) 3.0 (2006):

beatitude
    n 1: a state of supreme happiness [syn: blessedness,
         beatitude, beatification]
    2: one of the eight sayings of Jesus at the beginning of the
       Sermon on the Mount; in Latin each saying begins with
       `beatus' (blessed); "her favorite Beatitude is `Blessed are
       the meek for they shall inherit the earth'"

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "beatitude":
   beatification, bewitchment, blessedness, blessing, bliss,
   blissfulness, canonization, cheer, cheerfulness, cloud nine,
   consecration, dedication, delectation, delight, devotion, ecstasy,
   ecstatics, elation, enchantment, enshrinement, exaltation,
   exhilaration, exuberance, felicity, gaiety, gladness, glee,
   glorification, grace, hallowing, happiness, heaven, high spirits,
   intoxication, joy, joyance, joyfulness, justification,
   justification by works, overhappiness, overjoyfulness, paradise,
   purification, rapture, ravishment, sainthood, sainting,
   sanctification, setting apart, seventh heaven, state of grace,
   sunshine, transport, unalloyed happiness