indefatigability; indomitableness; unremitting tenacity
A yojijukugo describing a spirit that never yields or tires, often used in formal or literary contexts to praise perseverance.
His indomitable spirit finally brought the difficult project to success.
不屈不撓の努力を続ければ、いつか夢は叶う。
If you keep making unremitting efforts, your dream will come true someday.
Also means perseverance, but emphasizes patience and steadfastness rather than active resistance.
A yojijukugo composed of 不屈 (unyielding) and 不撓 (unbending). The exact historical origin is uncertain, but it is a classical Chinese-derived expression.