triphthong
/ˈtrɪfθɔŋ/
noun
- A complex vowel sound that begins with one vowel, glides through a second, and ends with a third, all in one syllable.
- Linguistics students learn to identify a triphthong by listening for three distinct vowel sounds in a single syllable.
- The word 'fire' contains a triphthong in some dialects.
- In English, the triphthong in 'hour' can be difficult for non-native speakers to pronounce.