定(さだ)か

さだか
na-adjective
definite, certain, clear
formaldescriptive
1. definite, certain, clear
Something that is clearly known or established. Most commonly used in the negative form 定かではない to express uncertainty.
記憶(きおく)が定(さだ)かではない。
My memory is not clear.
原因(げんいん)は定(さだ)かではないが、調査(ちょうさ)が進(すす)んでいる。
The cause is uncertain, but the investigation is progressing.
その伝説(でんせつ)が事実(じじつ)かどうかは定(さだ)かではないが、地元(じもと)では広(ひろ)く信(しん)じられている。
Whether the legend is true is not certain, but it is widely believed locally.

定(さだ)か is a na-adjective most commonly encountered in the negative form 定(さだ)かではない or 定(さだ)かでない, meaning "uncertain" or "not clear."

Forms

  • Negative: 定(さだ)かではない / 定(さだ)かでない
  • Modifier: 定(さだ)かな情報(じょうほう) (definite information)
  • Adverbial: 定(さだ)かに (definitely) — rare

Common collocations

Usage

The affirmative form (定(さだ)かな, 定(さだ)かだ) exists but is uncommon in modern Japanese. This word appears predominantly in negative constructions and in somewhat formal or written contexts.

Related Words

Synonym: 確(たし)か (certain, sure)
general
Added 2026.2.21 1:35 · Revised 2026.9.2 13:01
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