Translation guide
This guide covers how to express the idea of losing physical strength, power, intensity, or effectiveness in Japanese. It is organized by the specific nuance you want to convey, from general physical weakening to decline in influence or intensity.
To say that a person's physical strength or energy is declining, often due to age, illness, or fatigue.
The most common and natural way to say 'lose physical strength/stamina'. 体力 (physical strength) + が落ちる (to decline/drop).
最近、体力が落ちた気がする。
Lately, I feel like I've lost strength.
年を取ると体力が落ちる。
As you get older, you lose strength.
Intransitive verb meaning 'to weaken, to become weak'. Can refer to physical strength, health, or even mental state.
病気で体が弱った。
My body has weakened due to illness.
Literally 'strength leaves the body'. Used when you suddenly lose strength, often from shock, relief, or exhaustion.
その知らせを聞いて、全身の力が抜けた。
When I heard the news, all the strength drained from my body.
More formal/literary word for 'to decline, to weaken'. Often used for physical strength, mental faculties, or power over time.
加齢とともに筋力が衰える。
Muscle strength declines with age.
To describe something non-physical like wind, sound, or light becoming weaker.
Intransitive verb meaning 'to weaken, to abate'. Used for wind, rain, sound, etc.
風がだんだん弱まってきた。
The wind is gradually losing strength.
雨足が弱まった。
The rain has let up.
Can also be used for abstract forces like momentum or influence losing strength.
To say that something abstract like an argument, influence, or effect is becoming weaker or less effective.
Also used for abstract things like influence, power, or momentum.
彼の影響力は弱まっている。
His influence is losing strength.
Means 'to fade, to become dim'. Used for feelings, memories, consciousness, or effects.
Formal word meaning 'to decline, to drop'. Often used for ability, performance, or quality.
集中力が低下した。
My concentration weakened.
To describe something physical like a grip, structure, or material becoming weaker or looser.
Means 'to loosen, to become slack'. Used for screws, knots, grip, or tension.
ネジが緩んで、強度が落ちた。
The screw loosened and lost strength.
握力が緩んできた。
My grip is losing strength.
Simple adjectival phrase meaning 'to become weak'. Can be used for materials or structures.
この素材は熱で弱くなる。
This material loses strength when heated.
弱る (yowaru) is for living things becoming weak physically or mentally. 弱まる (yowamaru) is for forces, intensity, or abstract power weakening. 衰える (otoroeru) is more formal and implies a gradual decline over time, often used for aging or fading power.
祖父は最近めっきり弱った。
My grandfather has become noticeably weaker recently.
風が弱まるのを待とう。
Let's wait for the wind to die down.
記憶力が衰えてきた。
My memory has been declining.
Direct translations like 強さを失う (tsuyosa o ushinau) are not natural in most contexts. Use the specific phrases above depending on what kind of strength is being lost.
台風の勢力が衰えた。
The typhoon's strength has weakened.
薬の効果が薄れてきた。
The medicine's effect is wearing off.