決する|けっするkessuru[3]nakadaka (mid-high)

Common
Definitions
  1. suru verb (irregular), intransitive verb, transitive verbto decide; to determine; to resolve; to be decided
    まだどちらと決けっしたわけではありませんので、引き続ひきつづき成り行なりゆきを見守みまもりたいと思おもいます。↗
    I haven't decided either way. I want to keep an eye on how things go.
  2. 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.

Synonyms & antonyms
  • 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

Japanese definitions
  1. 決きまる。定さだまる。
  2. 決きめる。定さだめる。
  3. 決壊けっかいする。
Kanji in this word
English equivalents
See also

Say it right, write it right

Core lookup works fully offline, with cloud pronunciation and one-tap save & review. Free, no sign-up.

Free downloadWindowsFree downloadmacOSDownload on the App StoreGet it on Google Play
MobileiOS / Android

Android

QR code for the Google Play pageGet it on Google Play

Scan it with your Android phone to install, or search for “Tomoshi” on Google Play.

iOS

QR code for the App Store pageDownload on the App Store

Scan it with your iPhone camera to install, or search for “Tomoshi” in the App Store.

Install the browser extensionLook words up on any web page · Chrome / Edge / Safari

Screenshot of a Tomoshi lookup resultScreenshot of Tomoshi lookup results on a phone

Windows macOS Chrome / Edge / Safari extension iOS / Android