전무후무해요 · 전무후무했어요 · 전무후무한 (+noun)
unprecedented and likely never to be repeated
Example
그 선수는 전무후무한 기록을 세웠어요.
That athlete set a record that's never been matched and probably never will be.
Word parts
전 before+무 none+후 after+무 none
Literally 'none before, none after.'
Related words