Translation guide
The English verb "weaken" can describe making something physically weaker, reducing intensity or effect, or becoming less strong. This guide covers natural Japanese expressions for these meanings.
To cause someone or something to lose physical strength, power, or structural integrity.
Transitive verb meaning to weaken something physically or in terms of power. Common and versatile.
Causative form of 弱る (to weaken/decline), meaning to make someone/something weak, often implying exhaustion or decline.
長い病気が彼を弱らせた
The long illness weakened him.
Causative of 衰える (to decline), meaning to cause to decline or weaken, often used for abstract strength or vitality. More literary.
老化が体力を衰えさせる
Aging weakens physical strength.
To make something less intense, severe, or effective, such as an argument, influence, or impact.
Also used for abstract weakening, like reducing influence or intensity.
Means to soften, ease, or mitigate. Often used for pain, tension, or harshness.
Literally 'to dilute', used metaphorically to weaken concentration, impact, or flavor.
To lose strength, power, or intensity on its own.
Intransitive verb meaning to weaken, diminish, or abate. Commonly used for wind, rain, influence, etc.
風が弱まった
The wind weakened.
彼の影響力が弱まっている
His influence is weakening.
Intransitive verb meaning to weaken, decline, or become exhausted. Often used for living things or physical condition.
To decline, weaken, or deteriorate, often over time. Used for strength, health, or abilities.
To make a physical object or structure less strong or stable.
Phrase meaning 'make weak'. Simple and direct.
地震で建物が弱くなった
The building was weakened by the earthquake.
Means to make brittle or fragile. Used when something becomes easily breakable.
寒さでプラスチックがもろくなった
The cold weakened the plastic (made it brittle).
弱める is transitive (someone weakens something), while 弱まる is intransitive (something weakens on its own). Choose based on whether there is a direct actor.
English 'weaken' is often used for arguments, evidence, or resolve. In Japanese, direct translation with 弱める may sound unnatural. Consider 説得力を欠く (lack persuasiveness) or 効果が薄れる (effect fades) instead.
その証拠で彼の主張は弱まった
The evidence weakened his argument.
主張を薄める
water down the argument
My grandmother has weakened recently.