epochal

listen to the pronunciation of epochal
English - English
highly important or significant; monumentous, epoch-making
of or pertaining to an epoch
highly significant or important especially bringing about or marking the beginning of a new development or era; "epochal decisions made by Roosevelt and Churchill"; "an epoch-making discovery"
Belonging to an epoch; of the nature of an epoch
{s} of or pertaining to an age, of an era; momentous