Mono vs. Solo

In music, a solo is a piece or a section of a piece played or sung by a single performer. In practice this means a number of different things, depending on the type of music and the context.

The word is also used for the act of performing a solo, and sometimes for the performer (more often a soloist).

The plural is 'soli' or 'solos'. In some context these are interchangeable, but 'soli' tends to be restricted to classical music, and tends to refer to either the solo performers or the solo passages in a single piece: it would not often be used to refer to several pieces that happen to be for single performers.