夜中

Compound of 夜 (yo, “night”) +‎ 中 (naka, “middle”).[1][2]

• Kun’yomi
  • (Tokyo) よなか​ [yònákáꜜ] (Odaka – [3])[2][3]
  • IPA^(key): [jo̞na̠ka̠]

夜中 (hiragana よなか, rōmaji yonaka)

1. late at night, the middle of the night
2. midnight

   Synonym: 真夜中 (mayonaka)

The midnight sense of specifically at 12:00 AM is more commonly expressed by the term 真夜中 (mayonaka).

Apparently from Middle Chinese 夜中 (MC jia^H ʈɨuŋ).

• On’yomi: Goon
  • (Tokyo) や​ちゅう [yáꜜchùù] (Atamadaka – [1])[2][3]
  • (Tokyo) やちゅう [yàchúú] (Heiban – [0])[2][3]
  • IPA^(key): [ja̠t͡ɕɨᵝː]

夜中 (hiragana やちゅう, rōmaji yachū)

1. nighttime, the night, the period of time during the night

Compound of 夜 (yo, “night”) +‎ 中 (jū, “during, throughout”).[1][2]

• Yutōyomi
  • (Tokyo) よじゅう [yòjúú] (Heiban – [0])[2]
  • IPA^(key): [jo̞ʑɨᵝː]

夜中 (hiragana よじゅう, rōmaji yojū, historical hiragana よぢゆう)

1. the entire night, the period of time throughout the night