vowel /ˈvaʊ.əl/noun 2verb 1forms 5 noun2 •A sound produced by the vocal cords with relatively little restriction of the oral cavity, forming the prominent sound of a syllable.Hawaiian has either five or twenty-five vowels, depending on how they are counted. •A letter or diacritic representing the sound of a vowel; in English, the vowels are a, e, i, o, u, y (sometimes), and w (rarely).The word facetiously is spelled with all six vowels in alphabetical order.The word cwm, borrowed from Welsh, is an example of the letter w serving as a vowel in English. verb1 •To add vowel points to a consonantal script (e.g. niqqud in Hebrew or harakat in Arabic). formsvoweled · vowelled · voweling · vowelling · vowels