向こう

Two possible sources:

• From the nominalization of the 終止形 (shūshikei, “terminal form”) or 連体形 (rentaikei, “attributive form”) of the verb 向かう (mukau, “to face”). The modern pronunciation suggests that the morpheme boundary in the original verb muka.u has been lost.
• From the nominalization of the ウ音便 (-u onbin, “-u euphonic change”) form of the verb 向かう (mukau, “to face”) (cf. dialectal forms like 向こうて (mukōte)).

Accordingly, the historical kana spellings should be むかふ according to the former, and むかう according to the latter.^[1]

• (Tokyo) むこー [mùkóꜜò] (Nakadaka – [2])^[1]
• (Tokyo) むこー [mùkóó] (Heiban – [0])^[1][2]
• IPA^(key): [mɯ̟ko̞ː]

向(む)こう • (mukō) ^{←むかふ (mukafu)?}

1. the other side, the opposite side, across

   月(つき)の向(む)こう ― tsuki no mukō ― the farside of the moon

   道(みち)の向(む)こう ― michi no mukō ― across the street

2. the coming (several years etc.), the next (time period)
3. over there; a place fairly far from the speaker
4. the other concerned party; them, him, her

   Synonyms: 相(あい)手(て) (aite), 先(せん)方(ぽう) (senpō)

   • 1914, 夏目漱石 [Natsume Sōseki], chapter 7, in こゝろ [Kokoro], 下 先生と遺書 [Sensei's Testament]:

     どうして私(わたくし)の心(こころ)持(もち)がこう変(かわ)ったのだろう。いやどうして向(むこ)うがこう変(かわ)ったのだろう。

     Dōshite watakushi no kokoromochi ga kō kawatta no darō. Iya dōshite mukō ga kō kawatta no darō.

     Why had my feelings changed like this? Or rather, why had theirs changed like this?

• 向(むこう)三(さん)軒(げん)両(りょう)隣(どなり) (mukōsangen ryōdonari)

• “向こう”, in 漢字ぺディア [Kanjipedia]‎^[1] (in Japanese), The Japan Kanji Aptitude Testing Foundation, 2015–2026