ETYM Italian, from Latin solus alone. Related to Sole.
1. A flight in which the aircraft pilot is unaccompanied.
2. A musical composition for one performer.
3. Any activity that is performed alone without assistance.
In musical notation, a piece or passage written for one performer. Sometimes this implies an accompaniment provided by another player or players; for instance, Bach's solo cello sonatas are written for unaccompanied cello, but his solo violin concertos are written for a single violinist with orchestral accompaniment.

1. Accommodating one person
2. Of, relating to, or being a solo
3. Hit with no runners on base

Without a companion; alone

A musical composition for a single voice or instrument with or without accompaniment

To fly alone, without a co-pilot or passengers.