Chōonpu
vowel length mark in Japanese
The chōonpu (Japanese: 長音符; lit. "long sound symbol"), also known as chōonkigō (長音記号), onbiki (音引き), bōbiki (棒引き), or Katakana-Hiragana Prolonged Sound Mark by the Unicode Consortium, is a Japanese symbol that indicates a chōon, or a long vowel of two morae in length. Its form is a horizontal or vertical line in the center of the text with the width of one kanji or kana character. It is written horizontally in horizontal text and vertically in vertical text (ー). The chōonpu is usually used to indicate a long vowel sound in katakana writing and rarely in hiragana writing. The chōonpu is a distinct mark from the dash, and in most Japanese typefaces it can easily be distinguished. In horizontal writing it is similar in appearance to, but should not be confused with, the kanji character 一 ("one").
The symbol is sometimes used with hiragana, for example in the signs of ramen restaurants, which are often written らーめん in hiragana, while the most standard orthography would be in katakana: ラーメン. Canonically, however, hiragana never uses the chōonpu; instead, another vowel kana is used to express the long vowel. This applies in theory to onomatopoeia written in hiragana as well, but the use of the chōonpu is generally tolerated and common: おーい for おおい.
The public source identifies “Chōonpu” as vowel length mark in Japanese. This brief keeps that definition visible, then builds a research path around Chōonpu, vowel and length.
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This entry incorporates text from “Chōonpu” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.