害する|がいするgaisuru[3]nakadaka (mid-high)

JLPT N1approx.Common
Definitions
  1. suru verb (irregular), transitive verbto injure; to damage; to harm; to hurt
    その気候きこうで健康けんこうを害がいした。↗
    The climate affected his health.
  2. suru verb (irregular), transitive verbto kill
  3. suru verb (irregular), transitive verbto hinder; to obstruct
Conjugation
Dictionary form害する(がいする)
Polite (masu)害します(がいします)
Negative (nai)害しない(がいしない)
polite (masen)害しません(がいしません)
classical zu / nu害せず・害せぬ(がいせず・がいせぬ)
Past (ta)害した(がいした)
polite (mashita)害しました(がいしました)
Past negative (nakatta)害しなかった(がいしなかった)
polite (masen deshita)害しませんでした(がいしませんでした)
Te form害して(がいして)
Potential害できる(がいできる)
Passive害される(がいされる)
Causative害させる(がいさせる)
Causative passive害させられる(がいさせられる)
Conditional (ba)害すれば(がいすれば)
tara害したら(がいしたら)
Volitional害しよう(がいしよう)
polite (mashou)害しましょう(がいしましょう)
Imperative害しろ(がいしろ)

Common forms generated by rule; see the senses for honorific or irregular usage.

Synonyms & antonyms
  • Synonym損じるそんじるWrittenMeans damaging or injuring things; leans written. 「害する」focuses on harming health or feelings.
  • Synonym痛めるいためるNeutralTo injure or cause pain, and also to worry; 「害する」centers on doing harm.
  • Synonym毀損きそんWrittenDamages reputation or objects; often legal. 「害する」focuses on doing harm.
  • Synonym損ねるそこねるNeutralHarms mood or health, or means missing a chance, as in 「機嫌を損ねる」; 「害する」is more written.
  • Synonym損傷そんしょうNeutralNoun for injury or damage, objective in tone; 「害する」is a verb.
  • Synonym損害そんがいNeutralNoun covering losses and damage of all kinds—financial, physical, reputational, mental, as in 「精神的損害」; 「害する」is a verb.
  • Synonym傷害しょうがいWrittenNoun for inflicting bodily injury on someone; legal flavor.
  • Synonym破損はそんWrittenNoun for damage to objects; 「害する」focuses on doing harm.
  • Synonym損壊そんかいWrittenNoun for buildings, implements or vehicles being damaged; objective, news-report tone. 「害する」targets health or feelings.
  • Synonym殺害さつがいWrittenNoun for killing or murdering someone; 「害する」is broader.
  • Synonym傷つけるきずつけるNeutralInjures bodies or objects, and hurts feelings or pride, as in 「心を傷つける」; common in speech. For harming health, use 「害する」.
  • Synonym損なうそこなうNeutralHarms health or mood, as in 「健康を損なう」; close to 「害する」and common in both speech and writing.
  • Synonym害すがいすWrittenLiterary form of 「害する」; written style, same meaning.
  • Synonym殺めるあやめるWrittenWritten word for wounding or killing, with an archaic flavor; 「害する」is broader.
  • Synonym毀傷きしょうWrittenWritten word for destroying or injuring bodies and objects alike; rare today—use 「損傷」in everyday speech.
  • Related阻害そがいWrittenNoun for obstructing progress or development; 「害する」focuses on doing harm.
  • Related妨害ぼうがいNeutralNoun for hindering or interfering; 「害する」focuses on doing harm.
  • Related阻むはばむWrittenVerb for blocking someone's advance; 「害する」is about being harmful.
  • Related阻止そしNeutralNoun for stopping or preventing something; 「害する」focuses on doing harm.
  • Related邪魔じゃまNeutralBeing in the way or a nuisance; 「害する」focuses on harming health or feelings.
  • Related差し支えるさしつかえるNeutralTo interfere with something or cause inconvenience; 「害する」focuses on doing harm.
  • Related妨げるさまたげるNeutralTo hinder or obstruct; 「害する」is about being harmful.
  • Related毒するどくするWrittenTo corrupt or poison minds; 「害する」focuses on doing harm.
  • Related邪魔立てじゃまだてNeutralDeliberate obstruction or trouble-making; 「害する」focuses on doing harm.
  • Related討ち果たすうちはたすWrittenTo slay or cut down an enemy, with an archaic flavor; 「害する」can also mean to kill.
  • Antonym助けるたすけるNeutralTo help or assist; the opposite of harmful 「害する」.
  • Antonym益するえきするWrittenTo benefit or be of use to someone; the opposite of harmful 「害する」.

Use 「害する」for harming health or feelings or endangering others, as in 「健康を害する」「気分を害する」. You can also say 「健康を損なう」or 「機嫌を損ねる」. For injuring someone or something, use 「傷つける」; for benefiting, 「益する」.

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

Japanese definitions
  1. 悪化あっかさせる。損そこなう。
  2. 殺ころす。殺害さつがいする。
Kanji in this word
English equivalents
See also

JLPT vocabulary levels are community estimates, not official (no official lists have been published since the 2010 revision).

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