1. A project undertaken by a single person working independently, without collaborators or a team
He launched a solo project to develop the new software application.
Ele lançou um projeto solitário para desenvolver o novo aplicativo.
2. In the arts and music, a creative work created and performed by one individual artist
The musician decided to start a solo project apart from her band.
A musicista decidiu iniciar um projeto solitário apart from her banda.