正当|せいとうseitou[0]heiban (flat)

1. na-adjective, nounjust; justifiable; right; due; proper; equitable; reasonable; legitimate; legal; lawful
   先生せんせいは彼女かのじょに正当せいとうな取り扱とりあつかいをしなかった。↗

   The teacher didn't do her justice.

• Synonym公正こうせいWrittenWritten/formal prose. Fair and impartial, without favoritism, as in 「公正な判断」. It is about lack of bias, while 「正当」 is about according with reason or the law.
• SynonymフェアNeutralLoanword for fair; works for trade, competition and reporting, as in 「フェアな取引」. Leans colloquial.
• Synonym公平こうへいNeutralFairness in how people are treated — even-handedness, as in 「公平に分ける」. Emphasizes treating everyone alike.
• Synonym妥当だとうWrittenWritten/formal prose. Valid and reasonable, as in 「妥当な判断」. Emphasizes being just right for the case at hand.
• Synonym適正てきせいWrittenWritten/formal prose. Suitable and proper, as in 「適正価格」. Emphasizes conforming to a standard.
• Synonym正しいただしいNeutralThe most common everyday word for right or correct, with a very wide range. 「正当」 specifically implies having a legitimate reason.
• Synonym順当じゅんとうWrittenWritten/formal prose. Reasonable and only to be expected, as in 「順当に勝ち進む」. Emphasizes matching expectations.
• Synonym至当しとうFormalFormal. Perfectly proper and reasonable; rare in modern Japanese — say 「妥当」 in everyday contexts.
• Related適切てきせつNeutralAppropriate and well suited, as in 「適切な対応」. Emphasizes fitness for the situation.
• Related公明正大こうめいせいだいFormalFormal four-character idiom for someone open, upright and free of selfish motives; evaluates character.
• Related合理的ごうりてきNeutralRational and logical, as in 「合理的な説明」. Emphasizes sound reasoning.
• Related厳正げんせいFormalFormal. Strictly fair and impartial, as in 「厳正な審査」. Adds a nuance of rigor.
• Related穏当おんとうWrittenWritten/formal prose. Measured and appropriate, as in 「穏当な表現」. Emphasizes avoiding extremes.
• Related適法てきほうFormalFormal legal term: conforming to laws and regulations, as in 「適法な手続き」.
• Related合法ごうほうNeutralLegal in the strict sense, as in 「合法的な手段」. Focuses on the legal dimension.
• Related合法的ごうほうてきNeutralSame meaning as 「合法」; used as a na-adjective.
• Related筋の通ったすじのとおったCasualColloquial. Reasonable and consistent; stresses that an argument or claim holds up.
• Antonym不当ふとうNeutralAntonym: unjust, unreasonable or wrongful, as in 「不当解雇」. The direct opposite of 「正当」.

Use 「正当」 when something holds up because it accords with reason or the law, as in 「正当な理由」 and 「正当防衛」. For impartiality, say 「公正」; for what is fitting, 「妥当」 or 「適切」; for legality, 「合法」. 「不当」 is its opposite.

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

1. 正ただしくて、道理どうりにかなっていること。