A
diphthong ( or ) (
Greek: ,
diphthongos, literally "two sounds" or "two tones"), also known as a
gliding vowel, refers to two adjacent
vowel sounds occurring within the same
syllable. Technically, a diphthong is a vowel with two different targets: that is, the tongue (and/or other parts of the
speech apparatus) moves during the pronunciation of the vowel. In most
dialects of
English, the phrase
no highway cowboys has five distinct diphthongs, one in every
syllable.