““GLISSANDO. A term unfortunately used by composers anywhere but in Italy to indicate a rapid glide over the notes of a scale on keyboard instruments and the harp, as well as a slur with no definite intervals on strings and on the trombone. Italians do not use it for the simple reason that it is not an Italian word; in fact it is not a word in any language, but a hybrid form of the French glisser (to glide or slide) with an Italian present-participle ending. The proper Italian term is strisciando.”
“Glissando” in the fifth edition of Grove’s Dictionary of Music and Musicians, edited by Eric Blom and published in 1954.
Interessante o artigo, de Jessica Barbour, que se baseia nesta citação, sobre as origens e usos da palavra glissando, que aparentemente de italiana não tem nada.