Vowelonly

Vowelonly is a term used to describe strings that are composed exclusively of vowel letters. In linguistic and computational contexts, vowels typically include the letters a, e, i, o, u, and sometimes y when it functions as a vowel. A vowel-only string may appear in orthography, transcription, data processing, or word-game constraints rather than as a conventional word.

In English, there are a few true vowel-only words. The single-letter words “a” and “I” are the most common examples. Another well-known example is “euouae,” a medieval musical term often cited as the longest English word made entirely of vowels. Other languages may produce longer vowel-only sequences in borrowed terms or proper names, depending on orthographic conventions and the treatment of diacritics.

In puzzles, programming, and text processing, vowel-only constraints are used to shape inputs or clues. A typical regular expression to enforce a vowel-only string is ^[aeiou]+$ (with case-insensitive matching). When extending to languages with diacritics or extended vowels, one may need to include accented vowels and other vowel characters, or apply Unicode normalization to determine what counts as a vowel.

Variations may treat y as a vowel or not, and may broaden the set to include digraphs or diacritic variants. The term is descriptive and context-dependent rather than a standardized linguistic category. Related topics include vowels, consonants, vowel harmony, diacritics, regular expressions, and word games.