expression, ichidan verb
have a narrow escape from death
Idiomatic expression meaning to barely survive a life-threatening situation. Often used in past tense or as a set phrase.
あの事故で九死に一生を得た。
I narrowly escaped death in that accident.
危機一髪 is a noun/adverb meaning 'by a hair's breadth' or 'close call', while 九死に一生を得る is a verb phrase emphasizing survival from near-certain death.
Literally 'to obtain one life from nine deaths', a classical Chinese-derived idiom. The exact origin is uncertain, but it reflects the idea of surviving against overwhelming odds.