1. [n]  a flight in which the aircraft pilot is unaccompanied
2. [n]  any activity that is performed alone without assistance
3. [n]  a musical composition for one voice or instrument (with or without accompaniment)
4. [adv]  without anybody else; "the child stayed home alone"; "he flew solo"
5. [adj]  (music) composed or performed by a single voice or instrument; "a passage for solo clarinet"
6. [v]  fly alone, without a co-pilot or passengers

1. \So"lo\, a. (Music)
   Performing, or performed, alone; uncombined, except with
   subordinate parts, voices, or instruments; not concerted.
   

2. \So"lo\, n.; pl. E. {Solos}, 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.
   

[SOL (Semantic Operating Language) + LOGO]. A variant of LOGO with primitives for dealing with semantic networks and pattern matching rather than lists.

["A User-Friendly Software Environment for the Novice Programmer", M. Eisenstadt <[email protected]>, CACM 27(12):1056-1064 (1983)].