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