The Collaborative International Dictionary of English v.0.48:

Melisma \Me*lis"ma\, n.; pl. Melismata. [NL., fr. Gr. me`lisma
   a song.] (Mus.)
   (a) A piece of melody; a song or tune, -- as opposed to
       recitative or musical declamation.
   (b) A grace or embellishment.
       [1913 Webster]