空前绝后

unprecedented and never to be duplicated / the first and the last / unmatched / unique

front / forward / ahead / first / top (followed by a number) / future / ago / before / BC (e.g. 前293年) / former / formerly

empress / queen / (archaic) monarch / ruler

back / behind / rear / afterwards / after / later / post-

empty / air / sky / in vain

to empty / vacant / unoccupied / space / leisure / free time

to cut short / extinct / to disappear / to vanish / absolutely / by no means

variant of 絕|绝[jue2]

unprecedented