I started learning japanese recently, and I looked back at the kanji I've learned, and I simply can't think of any kanji with an onyomi longer than 2 morae.

Is there really no kanji with an onyomi longer than 2 morae, and if so, why?

  • 十【じゅう】、上【じょう】、食【しょく】……
    – Zhen Lin
    Apr 27, 2015 at 18:01
  • @ZhenLin The yoons modify the kana to the left, so じゅ kind of acts like a single character.
    – Alice Ryhl
    Apr 27, 2015 at 18:06
  • 1
    In terms of just kana, @ZhenLin is right. If we're talking syllables (or mora), then no, there is no 3-syllable kanji on-reading (at least in the jouyou list).
    – Cat
    Apr 27, 2015 at 18:07
  • 1
    I changed the question to ask about morae.
    – Alice Ryhl
    Apr 27, 2015 at 20:11
  • 2
    I'm pretty sure that's actually カイ and エ separately.
    – Zhen Lin
    Apr 27, 2015 at 21:37

1 Answer 1


Recall that on-yomi are derived from the Chinese pronunciation of characters, which are (with few exceptions) monosyllabic. The basic structure of a syllable in Middle Chinese is as follows:

  • An initial consonant
  • A glide
  • A vowel
  • A final – either another glide or a consonant, but not both

For instance, 關 (resp. 怪, 脚) is kwæn (resp. kwai, kjak) in Middle Chinese and has the kan-on クヮン (resp. クヮイ, キャク), but there are no syllables like kwain. Thus there is no way a trimoraic on-yomi would arise.

  • What happened here? has an onyomi of メエトル
    – Alice Ryhl
    May 16, 2015 at 20:52
  • 1
    That's not on-yomi. It's obviously "metre", from French.
    – Zhen Lin
    May 16, 2015 at 23:49
  • Sure, but why is it then listed under on?
    – Alice Ryhl
    May 17, 2015 at 7:34
  • Why don't you ask the person who created the website?
    – Zhen Lin
    May 17, 2015 at 8:09

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