Similar 音・訓読み: Coincidence, or something more?


Occasionally, some 漢字 will have quite similar 音読み and 訓読み; such as, for
instance 困; with 困{コン} and 困{こま}る; or 灰 with 灰{はい} and 灰{カイ}.

Are these cases exclusively coincidence, or are there situations in which
Chinese words have been fully internalised as Japanese words rather than Sino-
Japanese loanwords? (Or even; Japanese words exported to Chinese as fully
internalised loanwords?)

**Edit:**

Thanks to naruto's comment; I remembered the one I _really_ wanted to ask
about (it was nagging at me as I wrote the question): 死, with 死{し}ぬ and 死{シ}.




Looking at the etymologies independently:

### 灰

This term appears in the
[_Man'yōshū_](https://en.wikipedia.org/wiki/Man'y%C5%8Dsh%C5%AB) poetry
compilation completed circa 759, so this is an older word. The older kana
spelling of this was はひ, indicating an Old Japanese reading of `/papi/`.

Meanwhile, the on'yomi has an older kana spelling of くわい (probably realized as
`/kwai/`), closer to the Middle Chinese it came from, which has a
reconstructed reading of `/xwoj/` -- think of the `/x/` as a hard **H** like
in Scottish _loch_ , and think of the `/j/` on the end like a **Y**.

The older kun'yomi of `/papi/` doesn't overlap with the older on'yomi of
`/kwai/` in any way that I can find, so I think the similarity between modern
on'yomi _kai_ and kun'yomi _hai_ is purely a coincidence of historical
phonetic development.

### 困

The _komaru_ reading with a sense of "stuck, troubled" only seems to appear
from the early [Edo period](https://en.wikipedia.org/wiki/Edo_period), from
what I can find. I suspect this is an extension from / alteration of ancient
root verb 込{こ}む "to go into something; to put something into something else",
much like the English "stuck" can be interpreted as the passive participle
form of root verb "stick" (as in, "to _be_ stuck [into a bad situation]").

The older root's sense of "into" doesn't overlap much with the 困 kanji's
meaning of "besieged, troubled", so I suspect this similarity is another
coincidence of historical semantic development.

### Other cases

Although the above two are coincidental, there _are_ cases where the kun'yomi
developed from the on'yomi. One example is 文{ふみ}, where the kun'yomi of _fumi_
apparently came from an older on'yomi of _pun_. More at [the Wiktionary
entry](https://en.wiktionary.org/wiki/%E6%96%87#Japanese).

In general, sound similarities are _probably_ accidental. To find out for
sure, you have to dig into the historical development of each term.




Looking at the etymologies independently:

### 灰

This term appears in the
[_Man'yōshū_](https://en.wikipedia.org/wiki/Man'y%C5%8Dsh%C5%AB) poetry
compilation completed circa 759, so this is an older word. The older kana
spelling of this was はひ, indicating an Old Japanese reading of `/papi/`.

Meanwhile, the on'yomi has an older kana spelling of くわい (probably realized as
`/kwai/`), closer to the Middle Chinese it came from, which has a
reconstructed reading of `/xwoj/` -- think of the `/x/` as a hard **H** like
in Scottish _loch_ , and think of the `/j/` on the end like a **Y**.

The older kun'yomi of `/papi/` doesn't overlap with the older on'yomi of
`/kwai/` in any way that I can find, so I think the similarity between modern
on'yomi _kai_ and kun'yomi _hai_ is purely a coincidence of historical
phonetic development.

### 困

The _komaru_ reading with a sense of "stuck, troubled" only seems to appear
from the early [Edo period](https://en.wikipedia.org/wiki/Edo_period), from
what I can find. I suspect this is an extension from / alteration of ancient
root verb 込{こ}む "to go into something; to put something into something else",
much like the English "stuck" can be interpreted as the passive participle
form of root verb "stick" (as in, "to _be_ stuck [into a bad situation]").

The older root's sense of "into" doesn't overlap much with the 困 kanji's
meaning of "besieged, troubled", so I suspect this similarity is another
coincidence of historical semantic development.

### Other cases

Although the above two are coincidental, there _are_ cases where the kun'yomi
developed from the on'yomi. One example is 文{ふみ}, where the kun'yomi of _fumi_
apparently came from an older on'yomi of _pun_. More at [the Wiktionary
entry](https://en.wiktionary.org/wiki/%E6%96%87#Japanese).

In general, sound similarities are _probably_ accidental. To find out for
sure, you have to dig into the historical development of each term.

