一昨日

Compound of 一昨 (issaku-, “the previous... before...”) +‎ 日 (jitsu, “day”).

• On’yomi: Kan’on
  • (Tokyo) いっさ​くじつ [ìssáꜜkùjìtsù] (Nakadaka – [3])[1][2]
  • IPA^(key): [isːa̠kɯ̟ᵝʑit͡sɨᵝ]

一昨日 (hiragana いっさくじつ, rōmaji issakujitsu)

1. (formal) the day before yesterday, two days ago

• 一昨昨 (いっさくさく)日 (じつ) (issakusakujitsu, “three days ago”)

⟨woto₂ tu pi₁⟩ → */wotətupʲi/ → /wotot͡sufi/ → /otot͡suwi/ → /otot͡sui/

First attested in the Man'yōshū (c. 759 CE).

Originally a compound of 遠 (oto, “distant past”) + つ (tsu, Old Japanese case-marker particle) + 日 (hi, “day”).[1][3]

The kanji spelling is jukujikun (熟字訓).

• (Irregular reading)
  • (Tokyo) おとつ​い [òtótsúꜜì] (Nakadaka – [3])[1][2]
  • IPA^(key): [o̞to̞t͡sɨᵝi]

一昨日 (hiragana おとつい, rōmaji ototsui, historical hiragana をとつひ)

1. the day before yesterday, two days ago

Usually spelled in kana alone, rarely written with this kanji spelling.

• 一昨昨日 (さきおとつい) (saki-ototsui, “three days ago”)

/wotot͡sufi/ → /wototofi/ → /wototowi/ → /ototoi/

Shift from Old Japanese ototsui (see above).[1][3]

The kanji spelling is jukujikun (熟字訓).

• (Irregular reading)
  • (Tokyo) おとと​い [òtótóꜜì] (Nakadaka – [3])[1][2]
  • IPA^(key): [o̞to̞to̞i]

一昨日 (hiragana おととい, rōmaji ototoi, historical hiragana をととひ)

1. the day before yesterday, two days ago

Usually spelled in kana alone, rarely written with this kanji spelling.