In music, a glissando (plural: glissandi, abbreviated gliss.) is a glide from one pitch to another. It is an Italianized musical term derived from the French glisser, to glide. In some contexts it is distinguished from the continuous portamento. Some colloquial equivalents are slide, sweep (referring to the 'discrete glissando' effects on guitar & harp respectively), bend, or 'smear'.
Read more about Glissando: Glissando Vs. Portamento, 'Discrete Glissando', 'Continuous Glissando' or Portamento