invulnerability; immortality; insensitivity to pain
Describes a person or being that cannot be killed, wounded, or hurt. Often used figuratively for someone who seems unbreakable or never gets sick. The 'insensibility to pain' nuance is less common and usually appears in contexts of extreme resilience.
He is called the invulnerable man.
That player comes back right away even after an injury. It's as if he's invincible.
He gets up no matter how many times he falls—he seems immortal.
He faced the enemy's attacks as if he were invulnerable.
無敵 means invincible or unrivaled, especially in competition or battle, while 不死身 focuses specifically on being unkillable or unhurtable.
頑強 describes someone physically or mentally tough and resilient, while 不死身 goes further, suggesting the person literally cannot be killed or wounded.
タフ is a casual loanword for someone tough and hard to wear down, while 不死身 carries the stronger, often exaggerated sense of being truly unkillable.
Compound of 不 (not), 死 (death), and 身 (body). The literal meaning is 'undying body.' The word has been used in Japanese for centuries to describe mythical or legendary figures who cannot be killed.
That legendary warrior is known as an invincible man.