Noun
The word is derived from glissando
I do not think that any composer has ever asked for octave glissandi on the black keys, but there is a recording by Moriz Rosenthal of Chopin's Black-Key Etude in which he plays the short octave passage in both hands glissando: it hurts my hands just to think about it. Charles Rosen
String harmonic glissandi are discussed pp. 132-33; horn glissandi pp. 252-254 'Continuous glissando' or portamento Musical instruments with continuously variable pitch can effect a portamento over a substantial range. Source: Internet
The technique lends itself to glissandi (swoops up or down to a note); in addition it has the ability to evoke sounds of the human voice or natural noises. Source: Internet