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 many dialects of English, the phrase no highway cowboys /ˌnoʊ ˈhaɪweɪ ˈkaʊbɔɪz/ has five distinct diphthongs, one in every syllable.