单元音在一个音节的发音过程中不改变音质的单元音，如英文单词bed中的元音 A single vowel articulated without change in quality throughout the course of a syllable, as the vowel of English bed.
元音系统用于语言或方言的元音系统 A system of vowels used in a language or dialect.
书写单位；书写符号代表一个元音、辅音、音节、词或其它表达方式，并且不能进一步分解的书写符号 A written character that represents a vowel, consonant, syllable, word, or other expression and that cannot be further analyzed.
英语的元音字母有a，e，i，o，u，有时也包括y。 The vowels in the English alphabet are a, e, i, o, u, and, sometimes, y.
