I was wondering if anyone knows the etymology of this kanji 湯. I'm specifically looking for the Japanese variation of Bath or "yu". My wife's last name in kanji is 湯上 (Yugami).

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    Kanji come from China so there is no specific Japanese etymology for most kanji, unless they are one of the rare ones invented in Japan. – Super-User Sep 14 '20 at 3:38
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    In addition to those mentioned by @Ben, some characters were simplified in Japan in a way that differs from how they were simplified in China. So those also have a unique history. But 湯 doesn't belong to either of those categories. – Leebo Sep 14 '20 at 7:41

Looking up the etymology of the Japanese kanji "湯", you will find "From Old Japanese. Used in the Man'yōshū, completed some time after 759 CE."

And looking up a Chinese etymology dictionary named 象形字典:


Basically translated as:

"昜" is the original word for "陽", meaning natural warmth. You can find the character "昜" in "太陽", meaning "the sun". And the radical "氵" represents "water", pronounced 「さんずい」, in kanji such as "泳" or "波". So if you compose "氵" with "昜", you got "hot spring".

As for the pronunciation, "yu". According to this site, it's not an on-reading(音読み), but a kun-reading(訓読み), so it's not related to Chinese pinyin. (By the way, the 音読み is トウ).

And according to 語源由来辞典:

湯の語源には、温泉が湧き出る意味の「いづ(出)」の反や、「湧」の字⾳からなど諸説あり、有⼒とされているのは、「ゆるむ(緩む)」の意味とする説である。 冷⽔は縮まるようなものであるのに対し、湯は⾝も緩やかになるものなので妥当な説といえる。

The kun-reading(訓読み) is related to 「ゆるむ(緩む)」, which originates from "the relaxing feeling you get when you get into hot springs".


The meaning in modern Chinese is "soup" or "hot/boiling water". The simplified character is 汤. It's composed of a water radical 氵 and 昜, which means "to open out, to expand". The original meaning was "hot water, and the sound which emanates from it [熱水也從水昜聲]" — hence the usage of the 昜 component. (see 说文解字 at hanziyuan.net).

The modern Mandarin pronunciation of the 昜 component is (pinyin) yáng, which is somewhat similar to the Japanese pronunciation yu. I don't know if that's coincidental.

The page linked above also seems to say that 昜 is a phonetic component from "sundial" — which I can certainly imagine, with the sun 日 casting shadows 勿 on the sundial — but I don't see any indication of this character having that meaning in my Chinese dictionary.

You can also see the above linked website to see depictions of various script forms throughout history for that character.

As for the history of the pronunciation, the character's Chinese pronunciation hasn't changed much since middle Chinese (around the time that Japan became literate in Chinese characters). See Wiktionary entry for details. In pinyin, that's tāng, or /tʰɑŋ/ in IPA, so for the onyomi of tou, it's not a big leap to see how the velar nasal /ŋ/ opened up to a high back vowel /u/ when it crossed into Japanese. Or maybe that's just a long /o/, I'm not really an expert in Japanese (or anything).

Chinese/Japanese characters are one of the great things about east Asian cultures. There's a lot of history behind every one.

  • Ya, as you suspect, many of the Middle Chinese readings ending in //-ŋ// were borrowed into Old Japanese as ending in //-u// instead, since Old Japanese didn't actually allow any final (coda) consonants -- final ん didn't appear until centuries later. For the on'yomi of 湯, the modern kana spelling and reading is [とう]{tō}, but the historical kana spelling and original reading was [たう]{tau} -- tracing more clearly from Middle Chinese //tʰɑŋ//. So the phonetics went something like //tʰɑŋ// → //tau// (where //au// is like English ow!) → //tɔː// (where //ɔ// is like English awe) → //toː//. – Eiríkr Útlendi Nov 5 '20 at 18:39

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