In phonology, tenseness is a particular vowel quality that is phonemically contrastive in many languages, including English. It has also occasionally been used to describe contrasts in consonants. Unlike most distinctive features, the feature [tense] can be interpreted only relatively, that is, in a language like English that contrasts (e.g. beat) and (e.g. bit), the former can be described as a tense vowel while the latter is a lax vowel. Another example is Vietnamese, where the letters a and â represent lax vowels, and the letters a and o the corresponding tense vowels. Some languages like Spanish are often considered as having only tense vowels, but since the quality of tenseness is not a phonemic feature in this language, it cannot be applied to describe its vowels in any meaningful way.