もろい・脆いmoroi[2]nakadaka (mid-high)

1. i-adjectivebrittle; fragile; weak; frail
   彼かれが作つくった模型もけい飛行機ひこうきはもろかった。↗

   His paper plane was fragile.
2. i-adjectivetender-hearted; sentimental; easily moved
   彼女かのじょは情じょうにもろい。↗

   She is accessible to pity.

• Synonym脆弱ぜいじゃくWrittenWritten/formal. Fragile systems and structures, as in 「脆弱な地盤」 or 「セキュリティの脆弱性」; 脆い is for objects that break easily or feelings easily stirred.
• Synonym割れ易いわれやすいNeutralFor things that crack or split easily; used chiefly of physical objects such as glass and ceramics.
• Synonym壊れ易いこわれやすいNeutralFor things that break easily; suggests items that cannot withstand knocks or handling.
• Related弱いよわいNeutralThe most common and broadest word for weak; 脆い specifically suggests shattering at a touch or tears at the slightest thing.
• Related薄弱はくじゃくWrittenWritten/formal. Weakness of will, or thin evidence and foundations, as in 「意志薄弱」 and 「根拠が薄弱」; 脆い is about breaking or collapsing easily.
• RelatedデリケートNeutralLoanword for sensitive people or skin and for touchy issues, as in 「デリケートな肌」; can also mean delicately made and easily damaged.
• Related繊細せんさいNeutralFine, delicate and sensitive, as in 「繊細な神経」; stresses refinement and subtlety rather than breaking easily, though it can describe finely made, delicate things.
• Related軟弱なんじゃくWrittenWritten/formal. Weak and spineless, or soft, unstable ground; centres on lack of strength rather than breaking.
• Related弱々しいよわよわしいNeutralDescribes what looks weak and feeble, as in 「弱々しい声」; focuses on outward appearance rather than actual fragility.
• Related虚弱きょじゃくWrittenWritten/formal. Poor health and a weak constitution, as in 「虚弱体質」; specifically about the body.
• Relatedか弱いかよわいCasualColloquial. Delicate and frail in an endearing way, as in 「か弱い女性」; carries a note of tender sympathy.
• Related華奢きゃしゃNeutralSlender and delicate — a slight figure or flimsy furniture, as in 「華奢な体」; stresses daintiness rather than breaking.
• Related心弱いこころよわいNeutralTender-hearted and faint of heart — timid, quick to worry, slow to decide; examples are rare.
• Related柔弱にゅうじゃくWrittenWritten/formal. Weak and lacking backbone; carries a disparaging tone.
• Relatedひ弱ひよわCasualColloquial. Physically slight and weakly, as in 「ひ弱な子」; about a frail constitution.
• Antonym強いつよいNeutralStrong — the direct opposite of 脆い in its sense of easily broken or fragile.
• Antonym頑丈がんじょうNeutralSturdy and solid, the opposite of 脆い, as in 「頑丈な箱」.
• Antonym堅牢けんろうWrittenWritten/formal. Solid and durable, the opposite of 脆い.

Use 「脆い」 for things that break easily, structures that crumble, or hearts easily moved to tears, as in 「脆いガラス」 and 「涙脆い」. For fragile systems or structures choose 「脆弱」; for a delicate, frail person 「か弱い」; for a slender, dainty look 「華奢」. 「割れ易い」 and 「壊れ易い」 cover objects that crack or break, and 「弱い」 is the all-purpose word for weak. The opposites are 「頑丈」 and 「強い」.

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

1. 壊こわれやすい。破壊はかいされる余地よちがある。小ちいさなことで変形へんけいしたり、損傷そんしょうしたりする。
2. （組織そしきなどが崩くずれるさまが）あっけない。はかない。
3. 心こころが動揺どうようしやすく、小ちいさなことで涙なみだぐむ。同情どうじょうを抑おさえにくい。