por·ta·men·to (pôrt-mnt, pr-)
n. pl. por·ta·men·ti (-t) or por·ta·men·tos
In music, portamento is a gradual slide from one note to another. It is very similar to a glissando, but a glissando is deliberately written in the music by the composer and may be a long slide between two or three octaves or more. A portamento is a much shorter slide, usually between two notes which are quite close. Opera singers often used to slide from one note of a tune to another instead of singing each note separately and clearly. The habit of putting in portamento between notes spread to other instruments as well. When listening to recordings of violin playing from the early 20th century we can hear that the players used a lot of portamento.
Over the last half century portamento has gone out of fashion and singers and instrumentalists are taught not to slide from one note to another. However, there are some places, especially in opera, where it can be effective so long as it is not done all the time. It is a matter of taste.
In example one, the portamento is implied by the slur between the E flat and A flat in the first full measure.
Here’s an audio clip of no.1. Note that the portamento is subtle in this example.
In example no. 2, the portamento is indicated by the squiggly line leading to the grace note at the end of the first measure.
Here’s an audio clip of the second example. It is the female character’s first line that occurs around 1:40 or so.
Here’s two different performances of the Liszt transcriptions of the song. Notice the lack of portamento (it’s not really something that can be done on piano).
People often confuse portamento with portato, which means slightly detached – it’s somewhere between legato and staccato. Or rather, the terms used to be known as distinct, but now I believe, portamento is sometimes used to mean portato. Once Wikipedia returns, I’ll sort this out once and for all.
In the meantime, some more examples of the strictest definition of portamento.
Here’s a piece I sang in college. Definitely portamento involved here: