Translation guide
Describes someone who continues to work hard or show energy without becoming tired. In Japanese, this is often expressed through adjectives describing persistent effort, or through phrases about not showing fatigue.
To describe someone who works tirelessly and never seems to run out of energy.
Literally 'does not know fatigue'. A common and natural way to describe someone who seems tireless.
彼は疲れを知らない働き者だ。
He is an untiring worker.
To describe an activity or effort that is carried out without stopping or losing intensity.
疲れを知らない emphasizes the lack of fatigue, while 精力的 emphasizes the presence of energy. Both can translate 'untiring', but 精力的 is more about proactive vigor.
彼は疲れを知らない。
He never seems to get tired.
彼は精力的だ。
He is energetic/untiring.
Means 'energetic' or 'vigorous'. Often used to describe someone who tackles tasks with tireless energy.
彼女は精力的に活動している。
She is active untiringly.
A literary adjective meaning 'untiring' or 'unflagging'. Often used in formal or written contexts.
彼のたゆまぬ努力が実を結んだ。
His untiring efforts bore fruit.
Means 'without tiring' or 'without growing weary'. Very formal and literary.
彼は倦むことなく研究を続けた。
He continued his research untiringly.
Means 'incessant' or 'unceasing'. Used for efforts or actions that continue without pause.
彼の絶え間ない努力に感心した。
I was impressed by his untiring efforts.
Means 'constant' or 'unremitting'. Often used in phrases like 'untiring efforts'.
不断の努力が成功をもたらす。
Untiring effort brings success.