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. other side, opposite side, across

   月(つき)の向(む)こう

   tsuki no mukō

   the opposite side 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

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