決する|けっするkessuru[3]nakadaka (mid-high)
This browser can't play pronunciations (needs Safari 18.4 or later, or Chrome / Edge / Firefox).
- suru verb (irregular), intransitive verb, transitive verbto decide; to determine; to resolve; to be decided
- suru verb (irregular), intransitive verb, transitive verbto break and overflow (e.g. levee); to collapse; to give way; to breach
Conjugation
| Dictionary form | 決する(けっする) |
|---|---|
| Polite (masu) | 決します(けっします) |
| Negative (nai) | 決しない(けっしない) |
| polite (masen) | 決しません(けっしません) |
| classical zu / nu | 決せず・決せぬ(けっせず・けっせぬ) |
| Past (ta) | 決した(けっした) |
| polite (mashita) | 決しました(けっしました) |
| Past negative (nakatta) | 決しなかった(けっしなかった) |
| polite (masen deshita) | 決しませんでした(けっしませんでした) |
| Te form | 決して(けっして) |
| Potential | 決できる(けっできる) |
| Passive | 決される(けっされる) |
| Causative | 決させる(けっさせる) |
| Causative passive | 決させられる(けっさせられる) |
| Conditional (ba) | 決すれば(けっすれば) |
| tara | 決したら(けっしたら) |
| Volitional | 決しよう(けっしよう) |
| polite (mashou) | 決しましょう(けっしましょう) |
| Imperative | 決しろ(けっしろ) |
Common forms generated by rule; see the senses for honorific or irregular usage.
- Synonym決定けっていNeutralNeutral noun for a decision; the most widely used word of this set. 「決する」 is a written-style verb, seen in set phrases like 「雌雄を決する」.
- Synonym決めるきめるNeutralThe everyday verb for deciding, the most common choice in speech and more colloquial than 「決する」.
- Synonym確定かくていNeutralRefers to something being settled and fixed so it will not change, as in 「当選確定」.
- Synonym決意けついNeutralA noun for resolve that stresses the inner will to act; 「決する」 expresses the same idea in formal prose, as in 「意を決する」.
- Synonym決断けつだんNeutralA noun for making up one's mind firmly and without wavering; the stress is on decisiveness. 「決する」 is the written verb for deciding.
- Synonym決心けっしんNeutralA noun for the determination to do something; the everyday word for making up one's mind, whereas 「意を決する」 is the written counterpart.
- Related思い立つおもいたつNeutralA verb for suddenly hitting on the idea of doing something; it marks the first impulse. 「決する」 is the written verb for the decision itself.
- Related決定づけるけっていづけるNeutralA verb for playing the decisive role in an outcome, as in 「勝敗を決定づける」. 「決する」 is for the deciding itself.
- Related思い定めるおもいさだめるWrittenA written, rather literary verb for firmly making up one's mind. Like 「決する」, it belongs to formal prose, not everyday speech.
- Antonym迷うまようNeutralAn antonym: to waver, hesitate, and be unable to make up one's mind — the opposite of the decisive act 「決する」 describes.
- Antonym未決みけつWrittenA written-style noun for something not yet decided; also used for a case awaiting judgment. The opposite of what 「決する」 settles.
「決する」 is a written-style verb for deciding or resolving, as in 「雌雄を決する」 and 「意を決する」. In everyday speech use 「決める」; for the noun use 「決定」; for making up one's mind use 「決心」. 「確定」 is for something settled, 「決意」 for inner resolve, 「決断」 for deciding firmly without wavering, 「思い立つ」 for a sudden impulse, and 「迷う」 and 「未決」 for the undecided opposite.
Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only


