Source : Webster's Revised Unabridged Dictionary (1913)

Aria \A"ri*a\, n. [It., fr. L. a["e]r. See {Air}.] (Mus.)
   An air or song; a melody; a tune.

   Note: The Italian term is now mostly used for the more
         elaborate accompanied melodies sung by a single voice,
         in operas, oratorios, cantatas, anthems, etc., and not
         so much for simple airs or tunes.

Source : WordNet®

aria
     n 1: an elaborate song for solo voice
     2: an elaborate song for solo voice