noun, adverb
never to be seen again; unprecedented and unrepeatable
Often used in the set phrase 空前絶後 (くうぜんぜつご, 'unprecedented and never to be repeated') or as 絶後 alone to describe something so extraordinary it will likely never occur again. Can function as a noun or adverbially.
そのコンサートは空前絶後の大成功だった。
The concert was an unprecedented and unrepeatable huge success.
彼の記録は絶後のものと言われている。
His record is said to be something that will never be seen again.