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.