What exactly happened to the -ng ending in Japanese?

I think I’ve noticed a pattern when it comes to on’yomi with Chinese counterparts ending in
“-ng”. If the Chinese word ends in “-ing” then the corresponding on’yomi will have a similar initial consonant and be followed by えい or ょう. (Ex. 名 ming → めい/みょう or 生 sheng ->せい/しょう and the list goes on) If it ends in “ang” or “ong” it will end in おう (Ex. 常 chang → じょう or 同 tong → どう). I’m sure there is a pattern with “eng” endings as well, but I don’t know it. Is there a linguistic reason as to why this is seemingly the case?

My theory has always been that it disappeared as the Japanese language evolved.


The way I understand it, all onyomi readings are basically intact the way they were originally imported, so none of those have changed over time. If the monks recorded a reading as せい 1400 years ago, it’s せい today. If they recorded it as しょう, it’s しょう today. (I understand that some writing conventions have changed since then so they’re not literally written down the same way)

That being said, I know basically nothing about Chinese phonology. And also nothing about Chinese phonology from 1400 years ago.

But I think we can fairly confidently say no reading was ever imported sounding like “-eng” in Japanese.


That’s okay. It helps immensely to be able to see patterns like this, even if they aren’t exactly explainable. Languages are alive and they change often, so finding patterns is encouraged.

I was able to crack sokuons from as early as level 1 because I understood that Chinese words have been monosyllabic since the dawn of time as far as I can tell. (It also helps that I’m Vietnamese and took Chinese in high school).

Vowels tend to be lengthened before a voiced final consonant like that, so maybe they figured, if they couldn’t represent the -ng separately from -n, at least they could represent the longer vowel sound, to contrast it to a final -n or short vowel.

Also historically, Japanese had other syllables possible, for instance: in the S-row, there’s さう(そう), しやう(しょう), しう(しゅう), せう(しょう), しゆう(しゅう), and しよう(しょう). They were all reduced to syllables in the parentheses.

Modern Chinese, at least, does not make use of vowel length to produce new words, where Japanese does, so maybe this was a marker. They could use う in all instances to lengthen the vowel to indicate the previous -ng.

It can be noted that earlier Go-on readings with a long う vowel came back in later Kan-on as a long い vowel, showing the lengthening was preserved even when the vowel quality changed.


Modern putonghua (Mandarin) is a northern dialect that owes a lot to mongol, manchu and other invaders. The Chinese that was imported To japan in classical times is a bit closer to Cantonese and Min dialect although these have changed a lot from classical times. I actually don’t have as good a handle on how Japanese phonology has changed over time (and only the most basic grasp of th Chinese)

TL:DR things have diverged

There’s also some original Old Chinese readings that ended in consonants that got approximated to two moras in Japanese, like 作(さく) and others. But yeah, it’s been many centuries since these kanji readings were imported. During that time, not only Japanese, but also Chinese phonology has changed.

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