Seion

Seion may refer to:
 * a seion (せいおん, 清音), a type of mora (phonologic syllable) in Japonic languages which is denoted by a Kana character without any dakuten or handakuten diacritic, and that is part of the standard Gojuon alphabet in Japanese (as opposed to a dakuon or handakuon), i.e. a syllable with a leading unvoiced consonant or leading semivowel, or, at large, a vowel without any leading consonant
 * place names and chapel names in Wales, United Kingdom:
 * Seion Chapel, Cwmaman
 * as a given name:
 * Seion Darrell, a Bermudian football player