If someone is on their deathbed, they are in a bed and about to die.
例句
He promised his mother on her deathbed that he would never marry.他向垂危的母亲保证他绝不结婚。...after the man who murdered him nearly 40 years ago made a deathbed confession.在那个近40 年前谋杀了他的男子临终供认了罪行之后