Diphthong

Combination of two adjacent vowel sounds

A diphthong, also known as a gliding vowel or a vowel glide, is a combination of two adjacent vowel sounds within the same syllable. Technically, a diphthong is a vowel with two different targets: that is, the tongue moves during the pronunciation of the vowel. In most varieties of English, the phrase "no highway cowboy" has five distinct diphthongs, one in every syllable.

This keyword could refer to multiple things. Here are some suggestions: