A diphthong ['dɪfθɒŋ], from Ancient Greek δίφθογγος – díphthongos,two sounds‘, from δίς – dís – 'twice', and φθόγγος – phthóngos – 'sound', also known as a gliding vowel, 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 and other parts of the speech apparatus, moves during the pronunciation of the vowel. In most varieties of English, the phraseno highway cowboy‘ – [noʊ 'haɪweɪ 'kaʊbɔɪ] has five distinct diphthongs, one in every syllable