The Collaborative International Dictionary of English v.0.48:

Luscious \Lus"cious\, a. [Prob. for lustious, fr. lusty, or
   perh. a corruption of luxurious. Cf. Lush, Lusty.]
   [1913 Webster]
   1. Sweet; delicious; very grateful to the taste; toothsome;
      excessively sweet or rich.
      [1913 Webster]

            And raisins keep their luscious, native taste.
                                                  --Dryden.
      [1913 Webster]

   2. Cloying; fulsome.
      [1913 Webster]

            He had a tedious, luscious way of talking.
                                                  --Jeffrey.
      [1913 Webster]

   3. Gratifying a depraved sense; obscene. [R.] --Steele. --
      Lus"cious*ly, adv. -- Lus"cious*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

lusciousness
    n 1: extreme appetizingness [syn: delectability,
         deliciousness, lusciousness, toothsomeness]