The Collaborative International Dictionary of English v.0.48:

Cantabile \Can*ta"bi*le\, a. [It., cantare to sing.] (Mus.)
   In a melodious, flowing style; in a singing style, as opposed
   to bravura, recitativo, or parlando.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cantabile \Can*ta"bi*le\, n. (Mus.)
   A piece or passage, whether vocal or instrumental, peculiarly
   adapted to singing; -- sometimes called cantilena.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cantabile
    adj 1: smooth and flowing [syn: cantabile, singing]

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "cantabile":
   achingly sweet, agreeable, agreeable-sounding, appealing, aria,
   aria buffa, aria cantabile, aria da capo, aria da chiesa,
   aria di bravura, aria di coloratura, aria fugata, aria parlante,
   arietta, ariose, arioso, bravura, canorous, catchy, coloratura,
   dulcet, euphonic, euphonious, euphonous, fine-toned, golden,
   golden-tongued, golden-voiced, honeyed, melic, mellifluent,
   mellifluous, mellisonant, mellow, melodic, melodious,
   music-flowing, music-like, musical, pleasant, pleasant-sounding,
   recitative, rich, silver-toned, silver-tongued, silver-voiced,
   silvery, singable, solo, songful, songlike, sonorous, sweet,
   sweet-flowing, sweet-sounding, tunable, tuneful