A Dictionary of Music and Musicians/Portamento

PORTAMENTO (Fr. Porte de vois). A gradual 'carrying of the sound or voice with extreme smoothness from one note to another' [see vol. i. p. 43, note], which can only be really executed by the voice or by a bowed instrument. It is of frequent occurrence as a musical direction in vocal music or in that for stringed instruments, and also appears in music for keyed instruments. In old music one of the Agremens (see article before referred to) was so called, though of course it was always a very poor representation of the proper effect.

[ J. A. F. M. ]