Highly significant or important; momentous: epochal decisions made by Roosevelt and Churchill. (adjective)
Without parallel: epochal stupidity. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "epochal" in a sentence
"Clement Nyirenda also remarks on how the punditry got it wrong, and finds the voting pattern for the incumbent president's win epochal:"
"The word epochal is overstated, but it felt like it then and it has subsequently proved to be that."
"True, Barack Obama was elected president in a political upheaval that can only be described as epochal, but, well, you don't really think Cheney's just going to quietly vacate his office come January 20th, do you?"