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'"