epochal
adjective formal uk/ˈiː.pɒk.əl/ us/ˈep.ə.k.əl/
新纪元的，划时代的，有重大意义的
used to refer to times or events that are very important because they involve new developments and great change
An epochal shift in the global oil market is under way. 全球石油市场正在发生划时代的变化。
an epochal moment in British culture 英国文化史上的一个重要时刻