In Japanese, iteration marks (踊り字 odoriji "dancing mark" , 重ね字 kasaneji, 繰り返し記号 kurikaeshikigō, or 反復記号 hanpukukigō, "repetition symbols") are used to represent a duplicated character. For example, hitobito, "people" is usually written 人々, using the kanji for 人 with a repetition mark, 々, rather than 人人, using the same kanji twice. Japanese has three different iteration marks for its three writing systems, namely kanji (々), hiragana (ゝ), and katakana (ヽ); but only the kanji iteration mark is commonly used today.
In Chinese, the same mark (々) is used in shorthand to represent a doubled character, but it is never used in formal writing or printed matter, while in Japanese using the kanji iteration mark is usually the preferred form. In a tabulated table or list, vertical repetition can be represented by a ditto mark (〃).
In Thai, mai mayok (ๆ) represents a doubled word. Like Chinese, a repeated word is used for emphasis.
In English, lone quotation marks (") can informally represent a repeated word.
Iteration marks have been occasionally used for more than two thousand years in China. The bronzeware script on the bronze pot of the Zhou Dynasty, shown right, ends with "子二孫二寶用", where the small 二 (two) is used as iteration marks to mean "子子孫孫寶用".
While Japanese does not have a grammatical plural form per se, some kanji can be reduplicated to indicate plurality. This differs for Chinese, which normally only repeats characters for the purposes of adding emphasis, although there are some exceptions (eg. 人 rén person, 人人 rénrén everybody).
However, for some words duplication may alter the meaning:
The repetition mark is not used in every case where two identical characters appear side by side, but only where the repetition itself is etymologically significant. Where a character ends up appearing twice as part of a compound, it is usually written out in full:
The kanji repetition symbol is sometimes called noma because it looks like katakana no (ノ) and ma (マ). This symbol originates from a simplified form of the character 仝, a variant of 同 written in the Grass Script style.
Kana uses different iteration marks, one for hiragana, ゝ, and one for katakana, ヽ. The hiragana iteration mark is seen in some personal names like さゝき Sasaki or おゝの Ōno, and it forms part of the formal name of the car company . The kana iteration marks can be combined with the dakuten voicing mark to indicate that the repeated syllable should be voiced, for example みすゞ Misuzu. If the first syllable is already voiced, for example じじ jiji, the voiced repetition mark still needs to be used: じゞ rather than じゝ, which would be read as jishi.
While widespread in old Japanese texts, the kana iteration marks are generally not used in modern Japanese outside proper names, though they may appear in informal handwritten texts.
In addition to the single-character iteration marks, there are also two-character repeat marks. They are used in vertical writing only, and they are effectively obsolete in modern Japanese. The vertical kana repeat marks 〱 (unvoiced) and 〲 (voiced) resemble the hiragana character ku (く), giving them their name, . They stretch to fill the space typically occupied by two characters. When these need to be used on the Internet to faithfully represent old texts, ／＼ and ／″＼ are often used instead, as there is no horizontal equivalent.
If a dakuten (voiced mark) is added, it applies to the first sound of the repeated word. For example, tokorodokoro could be written vertically as ところ／″＼; the voiced iteration mark only applies to the first sound と.
Alternatively, multiple single-character iteration marks can be used, as in ところゞゝゝ tokorodokoro or 馬鹿々々しい bakabakashii. This practice is also uncommon in modern writing, though it is occasionally seen in horizontal writing as a substitute for the vertical repeat mark.
Unlike the kana iteration mark, if the first kana is voiced, the unvoiced version 〱 alone will repeat the voiced sound.