確か・確・慥か|たしかtashika[1]atamadaka (head-high)

1. na-adjectivesure; certain; positive; definite
   彼かれが間違まちがっているのは確たしかです。↗

   It is certain that he is wrong.
2. na-adjectivereliable; trustworthy; safe; sound; firm; accurate; correct; exact
   私はそのニュースを確たしかな筋すじから得えた。↗

   I got the news from a reliable source.
3. adverbIf I'm not mistaken; If I remember correctly; If I remember rightly
   これは確たしか淡水魚たんすいぎょだと思おもいます。↗

   I believe this fish is a freshwater fish.

• Synonym定かさだかWrittenWritten style, usually in the negative as 「定かではない」, meaning unclear or uncertain; 「確か」 works in both affirmative and negative sentences.
• Synonym確実かくじつNeutralRefers to something certain and sure not to fail, as in 「確実な方法」; an objective judgment. 「確か」 is more colloquial and can also mean 'if I remember right'.
• Synonym確かにたしかにNeutralAdverb meaning 'indeed, certainly', often concessive as in 「確かに〜が」. As an adverb 「確か」 instead means 'if I remember rightly'.
• Related明確めいかくWrittenWritten style: clear and definite, as in 「明確な目標」; stresses sharp boundaries. 「確か」 stresses being dependable.
• Related正確せいかくNeutralMeans accurate and free of error, as in 「正確な時間」. 「確か」 also covers reliability and 'if I remember right'.
• Related明瞭めいりょうWrittenWritten style: clear and distinct, as in 「明瞭な発音」; stresses being easy to make out. 「確か」 stresses being reliable and correct.
• Related手堅いてがたいCasualColloquial: steady and safe, no risk-taking, as in 「手堅い商売」; mostly evaluates methods. 「確か」 has wider uses.
• Related的確てきかくNeutralMeans accurate and apt, as in 「的確な判断」; stresses hitting the mark. 「確か」 stresses being reliable and correct.
• Related明らかあきらかNeutralMeans obvious and evident, as in 「明らかな間違い」; stresses that something is clear at a glance. 「確か」 stresses reliability.
• Related決定的けっていてきWrittenWritten style: nearly settled and decisive, as in 「決定的な瞬間」; stresses determining the outcome. 「確か」 stresses being reliable.
• Related明白めいはくWrittenWritten style: plain and beyond doubt, as in 「明白な事実」. In everyday speech 「明らか」 or 「確か」 is used instead.
• Related堅実けんじつWrittenWritten style: steady and solid in manner, as in 「堅実な経営」; stresses avoiding risk. 「確か」 is not specifically about one's manner.
• Related危なげないあぶなげないCasualColloquial: safe and steady with no risk, as in 「危なげない勝利」; mostly evaluates matches and performances. 「確か」 has wider uses.
• Related明解めいかいWrittenWritten style: describes clear, easy-to-follow explanations, as in 「明解な解説」; also common in book titles. Unlike 「確か」, it never means reliable.
• Related真正しんせいWrittenWritten style: genuine and authentic, as in 「真正の芸術」; stresses true rather than fake. 「確か」 stresses being reliable and correct.
• Related確定的かくていてきWrittenWritten style: already decided and unchangeable, as in 「確定的な証拠」; the conclusion is settled. 「確か」 stresses being reliable and free of error.
• Related精確せいかくWrittenWritten style: detailed and precise, used mainly for data and measurements; stresses fineness more than 「正確」. 「確か」 does not stress fine detail.
• Related信頼のおけるしんらいのおけるNeutralMeans trustworthy, as in 「信頼のおける情報」; used only before nouns. 「確か」 is used more freely.
• Antonym不確かふたしかNeutralThe opposite of 「確か」: uncertain and unreliable, as in 「不確かな情報」.
• Antonym曖昧あいまいNeutralThe opposite of 「確か」: vague and ambiguous, as in 「曖昧な返事」; stresses an unclear attitude or wording.

For 'sure, reliable' in everyday use, 「確か」 is the default. Choose 「確実」 for objective certainty, 「正確」 for accuracy, 「明確」 for clear definition, 「的確」 for apt, on-target judgments, and 「明らか」 for the obvious. Uncertain or unreliable things take 「不確か」 or 「曖昧」.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. (しかと、しっかと) 確たしかであるさま。はっきりしているさま。
2. (しっか-り) 確たしかであるさま。