一昨日(いっさくじつ)

いっさくじつ
noun
the day before yesterday (formal)
1. the day before yesterday (formal)
The formal or literary reading of 一昨日, used in written language, news, and formal speech. The everyday reading is おととい.
一昨日(いっさくじつ)の会議(かいぎ)の議事録(ぎじろく)を確認(かくにん)した。
I checked the minutes from the meeting the day before yesterday.
一昨日(いっさくじつ)から気温(きおん)が急(きゅう)に下(さ)がった。
The temperature dropped suddenly starting from the day before yesterday.
一昨日(いっさくじつ)付(づ)けの新聞(しんぶん)に関連(かんれん)記事(きじ)が掲載(けいさい)されていた。
A related article was published in the newspaper dated the day before yesterday.

一昨日(いっさくじつ) is the formal reading of 一昨日(おととい) (the day before yesterday). Both use the same kanji but differ in register.

READING CONTRAST:

  • おととい: everyday conversation, casual speech
  • いっさくじつ: news broadcasts, official documents, formal writing, business contexts

PATTERN:

The 一昨(いっさく)〜 prefix means "the ~ before last" and applies to other time words:

  • 一昨日(いっさくじつ): the day before yesterday
  • 一昨年(いっさくねん): the year before last
  • 一昨晩(いっさくばん): the night before last

SIMILAR TIME WORDS:

  • 昨日(きのう)/昨日(さくじつ): yesterday (casual/formal)
  • 明後日(あさって)/明後日(みょうごにち): the day after tomorrow (casual/formal)
general
Added 2026.3.14 11:12 · Revised 2026.3.30 12:38
16500/16681_issakujitsu