脆弱|ぜいじゃくzeijaku[0]heiban (flat)

1. na-adjective, nounweak; frail; fragile
   脆弱ぜいじゃくで力ちからの無ない、ただの人間にんげんなんだ。↗

   She's weak, powerless. A mere human.

• SynonymもろいNeutralAn i-adjective for things that break or crumble easily, also soft-hearted as in 「涙もろい」; colloquial, while 「脆弱」 is written/formal.
• Synonymか弱いかよわいNeutralDelicately frail, said mostly of women and children; evokes tender sympathy.
• Synonym虚弱きょじゃくNeutralA weak constitution, as in 「虚弱体質」; about the body, not structures or systems.
• Synonym弱いよわいNeutralThe broadest word for weak or poor at something, as in 「地震に弱い建物」; 「脆弱」 is more formal and stresses collapse.
• Synonym軟弱なんじゃくNeutralSoft and lacking firmness, as in 「軟弱地盤」; also a weak-willed character.
• Synonym薄弱はくじゃくNeutralWeakness of will or of evidence, as in 「意志薄弱」「根拠薄弱」.
• Synonym弱々しいよわよわしいNeutralLooks weak, as in 「弱々しい声」; about outward impression rather than actual fragility.
• Synonym割れ易いわれやすいNeutralFor things that crack or shatter easily, such as glass or ceramics; purely physical brittleness, with no use for systems or character.
• Synonym壊れ易いこわれやすいNeutralEasily broken or damaged; the focus is usually on objects, like the fragile items marked on parcels, rather than on structures giving way.
• RelatedデリケートNeutralA loanword for sensitive people or skin and delicate issues; stresses fine sensitivity, not proneness to collapse.
• Related繊細せんさいNeutralFine and delicate, mostly of sensitivity or refined workmanship; positive in tone, whereas 「脆弱」 is negative.
• Related不安定ふあんていNeutralUnstable, as in 「情緒不安定」; stresses wavering and fluctuation rather than weakness that invites collapse.
• Related非力ひりきNeutralLacking strength or ability, as in 「非力ながら」; often used as a humble expression.
• Related華奢きゃしゃNeutralA slender figure, or furniture that is lightly built and flimsy; carries a dainty, graceful nuance rather than weakness.
• Related柔弱にゅうじゃくWrittenA written/formal word for lacking in spirit or physical strength; covers both character and body.
• Related羸弱るいじゃくWrittenPhysical weakness; highly literary and rarely used.
• Relatedひ弱ひよわNeutralFrail or sickly-looking; said mostly of people or physiques; colloquial.
• Related心弱いこころよわいNeutralTimid, faint-hearted and indecisive; purely psychological, not about objects or structures.
• Antonym頑丈がんじょうNeutralAntonym: sturdy and solid; the opposite of collapse-prone 「脆弱」.
• Antonym強固きょうこNeutralAntonym: firm and unshakeable, said of foundations and will; the opposite of 「脆弱」.

Use 「脆弱」 for structures, systems or foundations that are weak and liable to collapse — 「脆弱な地盤」, 「セキュリティの脆弱性」; it leans written/formal. For things that break easily say 「脆い」; for a weak body, 「虚弱」; the all-purpose everyday word is 「弱い」. For unstable conditions use 「不安定」, for weak will or evidence 「薄弱」, for soft ground 「軟弱」. The antonyms are 「頑丈」 (sturdy) and 「強固」 (firm).

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

1. 脆もろく弱よわいこと。また、そのさま。