so·lo / ˈsōlō/ • n. (pl. -los) 1. a thing done by one person unaccompanied, in particular: ∎  (pl. so·los or so·li / ˈsōlē/ ) a piece of vocal or instrumental music or a dance, or a part or passage in one, for one performer. ∎  an unaccompanied flight by a pilot in an aircraft.2. a card game in which one player plays against the others in an attempt to win a specified number of tricks. • adj. & adv. for or done by one person alone; unaccompanied: [as adj.] a solo album | [as adv.] she'd spent most of her life flying solo. • v. (so·loes, so·loed) [intr.] perform something unaccompanied, in particular: ∎  perform an unaccompanied piece of music or a part or passage in one. ∎  fly an aircraft unaccompanied. ∎  undertake solo climbing.

solo (It.). Alone. A vocal or instr. piece or passage perf. by one performer, i.e. a solo song is for one singer, with or without acc. The solo instr. in a conc. might also be acc. by a solo passage for one of the orch. players. The word soloistic is sometimes used to denote a composer's use of the individual qualities of an instr., but its use is to be regretted.

solo (mus.) part to be sung or played by one performer alone. XVII. — It. solo :- L. sōlus SOLE2.
Hence soloist XIX.