epoch

Example:Her discovery was epoch-making in the field of astronomy.

Definition:reshaping; revolutionizing; completely changing an established situation or practice; of or relating to an epoch or epochal event or development; especially, unusually important and influential

Example:The fall of the Roman Empire marked the beginning of the Medieval epoch in Europe.

Definition:The medieval period, a significant stage in the European history from the 5th to the 15th century

Example:The transition from the stone age epoch to the bronze age epoch marked a significant advancement in technology.

Definition:A significant period in human prehistory characterized by the use of stone tools