確実|かくじつkakujitsu[0]heiban (flat)

1. na-adjective, nouncertain; sure; definite; reliable; sound; solid; safe; secure
   これは遅おそいけど確実かくじつな方法ほうほうだ。↗

   This is a slow but certain way.

• Synonym定かさだかWrittenMostly in negatives like 「定かではない」, meaning clearly settled; 「確実」 works in affirmative judgments and can also describe a sure, reliable way of doing things.
• Synonym手堅いてがたいNeutralDescribes a steady, cautious approach that avoids taking chances, as in 「手堅い投資」 or 「手堅い守り」; 「確実」 stresses that nothing will go wrong and success is assured.
• Synonym危なげないあぶなげないNeutralSuggests steady performance with no visible risk, as in 「危なげない勝利」; mostly evaluates how something is done. 「確実」 stresses a certain outcome.
• Synonym確かたしかNeutralEveryday na-adjective for certain and reliable, more common in speech; as an adverb it also hedges a memory, as in 「確か三時だった」.
• Synonym確かにたしかにNeutralAn adverb meaning indeed or certainly, as in 「確かに受け取りました」; also concedes a point before countering it. 「確実」 is a na-adjective; its adverb form is 「確実に」.
• Synonym相違なくそういなくFormalA formal adverb seen in certificates and application forms to confirm the statement is accurate, as in 「上記の通り相違なく」; in speech say 「確かに」 or 「間違いなく」.
• Related大丈夫だいじょうぶCasualColloquial: no problem, safe, dependable — reassures subjectively. 「確実」 is an objective judgment that something is certain, as in 「合格は確実だ」.
• Related決定的けっていてきNeutralMeans nearly settled or decisive, as in 「決定的な証拠」; 「確実」 stresses reliability and that something will surely happen, not a decisive role.
• Related正確せいかくNeutralMeans accurate and free of error, as in 「正確な時間」 — precision is the focus. 「確実」 stresses that something will surely happen or can be depended on.
• 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」; typically describes people or sources of information. 「確実」 stresses that the matter itself is certain.
• Related確定的かくていてきWrittenWritten style: already decided and unchangeable, as in 「確定的な結論」. 「確実」 also covers judgments about the future, as in 「合格は確実だ」.
• Antonym不確実ふかくじつWrittenThe direct negation of 「確実」: uncertain and unreliable, as in 「不確実な情報」. It leans written; in speech 「不確か」 is more common.
• Antonym曖昧あいまいNeutralVague and unclear, as in 「曖昧な返事」 — the opposite of 「確実」's clear certainty, focusing on unclear statements or attitudes.

Use 「確実」 for a firm judgment that something is certain or for doing something with no room for error. In everyday speech 「確か」 is the usual choice. For a steady, safe approach say 「手堅い」, for accuracy 「正確」, and to reassure someone 「大丈夫」.

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

1. 事実じじつや将来しょうらいの事象じしょうなどに関かんする判断はんだんにおいて、確たしかで間違まちがいのない様子ようす。
2. 間違まちがいや失敗しっぱいのないようしっかりと行おこなう様子ようす。