The Collaborative International Dictionary of English v.0.48:

Solo \So"lo\ (s[=o]"l[-o]), n.; pl. E. Solos (s[=o]"l[=o]z),
   It. Soli. [It., from L. solus alone. See Sole, a.] (Mus.)
   A tune, air, strain, or a whole piece, played by a single
   person on an instrument, or sung by a single voice.
   [1913 Webster]