A Dictionary of Music and Musicians/Solo
SOLO (Ital. 'alone '). A piece or passage executed by one voice or performer. Airs are solos; a pianoforte piece for 2 hands is a pianoforte solo. A violin solo, strictly speaking, is a piece for the violin alone, like Bach's unaccompanied sonatas; but the term is often used loosely for a concerto or other piece in which the solo instrument is accompanied by the band, the pianoforte, etc.
In an orchestral piece where one instrument has a passage which is intended to sound out prominently, it is marked 'Solo,' as in the second subject of the Adagio in Beethoven's Symphony no. 4, which is for the 1st clarinet, and marked Solo; in the flute solo near the end of the working-out in the Leonora Overture (where, however, the bassoon, equally solo, is merely marked '1.'); and in a thousand other instances. In arrangements of pianoforte concertos for 2 hands, the entry of the solo instrument is marked Solo, to distinguish it from the compressed accompaniment.[ G. ]