The Collaborative International Dictionary of English v.0.48:

Soprano \So*pra"no\, n.; pl. E. Sopranos, It. Soprani. [It.,
   fr. soprano superior, highest, fr. sopra above, L. supra. See
   Sovereign.] (Mus.)
   (a) The treble; the highest vocal register; the highest kind
       of female or boy's voice; the upper part in harmony for
       mixed voices.
   (b) A singer, commonly a woman, with a treble voice.
       [1913 Webster]