In phonetics, a diphthong is a vowel combination usually involving a quick but smooth movement from one vowel to another, often interpreted by listeners as a single vowel sound or phoneme. While "pure" vowels are said to have one target tongue position, diphthongs have a moving tongue. Pure vowels are represented in phonetic script by one symbol: English "seem" as [si:m], for example. Diphthongs are represented by two symbols, for example English "same" as [seim], where the two vowel symbols are intended to represent approximately the beginning and ending tongue positions.

Diphthongs in English: [5]

  • [au] as in house
  • [ai] as in kite
  • [ei] as in same
  • [@u] as in hope
  • [oi] as in join. (see SAMPA/English for more)

Diphthongs in Spanish:
  • [ja] as in comedia
  • [je] as in tierra
  • [jo] as in dió
  • [wa] as in guante
  • [we] as in fuego
  • [wi] as in pingüino
  • [aj] as in hay
  • [ej] as in rey
  • [oj] as in hoy
  • [aw] as in Jauja

Diphthongs in French:
  • [wa] and in roi
  • [wi] as in oui
  • [Hi] as in huit
  • [ja~] as in bien
  • [jE] as in Aričge

Diphthongs in German:
  • [aj] as in Reich
  • [aw] as in Maus
  • [oj] as in neu