性質|せいしつseishitsu[0]heiban (flat)

1. nounnature (of a person); disposition; temperament; character
   彼かれは性質せいしつが頑固がんこだ。↗

   He is obstinate in disposition.
2. nounquality; inherent characteristic; property; nature; (chemical) behavior

• Synonym性格せいかくNeutralA person's character, but also the nature of things, as in 「事件の性格」. 「性質」 is more objective and covers the properties of materials too.
• Synonym質しつNeutralQuality in the sense of how good or bad something is, as in 「質が高い」. It grades worth rather than describing what something is like.
• Synonym気質きしつNeutralA person's temperament — the innate pattern of emotional reactions; frequent in psychology. 「性質」 is broader and also covers the properties of things.
• Synonym人柄ひとがらNeutralA person's character as shown to others — the impression they give, as in 「人柄がいい」. It judges the person, not the properties of a thing.
• Synonym人格じんかくWrittenFormal word for character or personhood as a human being, as in 「人格を尊重する」.
• Synonym根性こんじょうNeutralGrit and staying power, but also one's basic nature, as in 「根性がある」.
• Synonym本性ほんしょうNeutralThe nature one is born with or one's true self, as in 「本性を現す」. Often carries a negative nuance.
• Synonym性根しょうねNeutralA person's fundamental disposition, as in 「性根を叩き直す」. Carries a colloquial, rough-edged flavour.
• Synonym性せいWrittenWritten word for nature, mostly used as a suffix in words like 「安全性」.
• Synonym資質ししつWrittenFormal word for innate aptitude or qualities, as in 「指導者の資質」. It covers talent as much as temperament.
• Synonym天性てんせいNeutralWhat one is born with — innate character or gift, as in 「天性の明るさ」. It stresses the inborn side.
• Synonym気性きしょうNeutralTemper — how easily one is roused, as in 「気性が激しい」. It centres on emotional expression rather than character as a whole.
• Synonym気心きごころNeutralThe temperament you come to know in someone close, as in 「気心が知れた」. It implies familiarity between people.
• Synonym性分しょうぶんNeutralAn inborn temperament one cannot change, as in 「損な性分」. It stresses the fixed, often troublesome side of one's makeup.
• Synonym真性しんせいWrittenWritten word meaning genuine or intrinsic; mostly in medical terms like 「真性包茎」.
• Synonym心根こころねNeutralThe heart at the bottom of a person — their true feelings and kindness, as in 「心根の優しい人」.
• SynonymキャラクターNeutralLoanword for personality, but also for fictional characters and roles in novels, manga and anime.
• SynonymパーソナリティーNeutralLoanword for personality or individuality; also a TV presenter.
• Synonym特性とくせいWrittenThe properties unique to a thing or person, as in 「素材の特性」「個人の特性」. A technical, written flavour.
• Synonym禀性ひんせいWrittenWritten word for an innate disposition; rare in modern Japanese.
• SynonymきっぷCasualColloquial. A person's spirit or mettle; 「気っ風がいい」 praises someone as forthright and open. Said of people or a region's people, never of things.
• Synonym性情せいじょうWrittenWritten, literary word for a person's disposition and feelings.
• Synonym賦性ふせいWrittenWritten word for an inborn nature; rare in modern Japanese.
• Synonym資性しせいWrittenWritten word for innate disposition and endowments; rare in modern Japanese.
• Synonym稟性ひんせいWrittenWritten word for an inborn nature, equivalent to 「禀性」; rare in modern Japanese.
• Related品性ひんせいWrittenFormal word for moral character, as in 「品性下劣」. It judges virtue and decency rather than personality at large.
• Related傾向けいこうNeutralA tendency or drift, as in 「増加傾向」「保守的な傾向」. 「性質」 names what something is like; 「傾向」 names the direction it leans.
• Related特色とくしょくNeutralDistinctive features that set something apart, as in 「地域の特色」. It carries a positive evaluation.

Use 「性質」 for the nature or properties of people and things, including materials. For a person's character pick 「性格」 or 「人柄」; for temper 「気性」; for what one is born with 「天性」. For distinctive properties use 「特性」, for what sets something apart 「特色」, for leanings 「傾向」. 「キャラクター」 and 「パーソナリティー」 are loanwords for personality. Others are narrower or literary: 「気質」 temperament, 「根性」 grit, 「本性」 true nature, 「品性」 moral character, and 「賦性」「稟性」, rare written words for innate disposition.

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

1. ある対象たいしょうを特徴とくちょうづける形態けいたいや機能きのう、傾向けいこう。