glissando

Glissando is an Italianized form of the French glissant, the present participle of glisser ('to slide, to slip'), which derives from a Frankish or Low German root related to Old English glīdan ('to glide'). The ultimate root is Proto-Germanic *glīdaną, which produced English 'glide,' 'glitter,' and — through a longer journey via Latin glacies ('ice') and French glace ('ice, mirror surface') — 'glacier.' The musical term is a hybrid: French glissant given an Italian gerund ending (-ando) to produce a word that looks Italian but is etymologically French, adopted into the international musical vocabulary because Italian was the dominant language of musical terminology in the eighteenth and nineteenth centuries. The word means, literally, 'sliding' or 'while sliding.'

As a musical technique, glissando describes the continuous slide between two notes — as opposed to a portamento, which is a brief connecting slide between two defined pitches. On a piano, a glissando involves dragging a finger rapidly across the white keys (or sometimes both black and white keys), producing a rapid cascading run in which each distinct pitch is heard briefly. On string instruments, the finger slides along the string while the bow sounds it, producing a continuous change in pitch rather than discrete notes. On the trombone, the slide mechanism allows a true continuous glissando — every frequency between two pitches can be produced. The harp glissando, in which the player sweeps through all strings, is one of the most familiar orchestral effects.

The glissando has distinct physical and psychological effects from other ornamentation. Where a trill or a turn repeats defined pitches in quick alternation, the glissando slides through the infinite gradations between pitches, implying all the frequencies that ordinary tonal music ignores. This gives glissando an inherent expressiveness: the slide through pitch carries emotional connotations of yearning, grief, humor, or (when extreme) comedy and caricature that discrete pitches cannot. The portamento of a Romantic singer — the slipping between notes in a melodic phrase — was considered the height of expressive art in the early nineteenth century and is now often heard as excessive; the glissando has more consistently retained its expressive force because it is usually more gestural, more obviously a special effect.

In twentieth-century music, the glissando became a technique of structural importance rather than merely ornamental use. Bartók's string writing extensively employs glissandi, often in startling contexts. George Gershwin's Rhapsody in Blue (1924) opens with one of the most famous glissandi in all of music — a clarinet slide from its lowest note upward through more than two octaves, a rising cry that launched American concert music into a new era. The slide that had been an ornament became a signature; the glacier root, which implies mass and slow inevitable movement, turns out to describe this clarinet cry quite well: unstoppable, elemental, transformative.