How to say "frail" in Japanese

Choosing the right word

弱いよわいJLPT N5approx.Common
i-adjectiveThe general word for weakness; 'frail' here means simply lacking strength or resilience. Use it for a frail person, frail health, or anything not strong — the default choice when no special nuance is needed.
それを言いわれると弱よわいなあ。↗
That sure puts me on the spot.
脆弱ぜいじゃくCommon
na-adjective, nounFrames 'frail' as fragility: something easily damaged or broken, lacking resilience. Choose it when vulnerability to damage is the point rather than a simple lack of strength.
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.
もろいJLPT N1approx.Common
i-adjectiveEmphasizes brittleness: things that break or crumble easily. Use for 'frail' when physical fragility or an easily-shattered quality is meant; usually written in kana.
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.
か弱いかよわいCommon
i-adjectiveDelicate, feeble frailty, typically of a person or creature — slight, delicate, and lacking strength. Carries a tender, sympathetic nuance, as of someone needing protection.
彼女かのじょの子こどもはか弱よわかった。↗
Her child was in delicate health.
弱々しいよわよわしいCommon
i-adjectiveDescribes something that seems weak and frail — a frail-seeming appearance, manner, or voice. It presents weakness as outwardly visible, an impression of frailty.
その弱々よわよわしい患者かんじゃは胃癌いがんに苦くるしんでいる。↗
The feeble patient is suffering from stomach cancer.

Use 「弱い」 for general weakness, 脆弱 for fragility and vulnerability to damage, 「もろい」 for brittleness, 「か弱い」 for delicate frailty of a person, and 「弱々しい」 for a weak, frail-seeming appearance.

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

Japanese equivalents

弱いよわいweak
脆弱ぜいじゃくweak
もろいbrittle
か弱いかよわいweak
弱々しいよわよわしいweak
体が弱いからだがよわいfrail
体の弱いからだのよわいfrail
吹けば飛ぶようふけばとぶようfrail
繊弱せんじゃくdelicate
なよっちいweak
よぼよぼdoddering
フレイル(being) frail
華奢きゃしゃfragile (e.g. furniture)
ひょろひょろlanky

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