epoch
Definitions
A particular period of time in history or a person's life, typically one marked by notable events or particular characteristics.
The beginning of a distinctive period in the history of anything.
A unit of time in geology that is a division of a period, or in astronomy, a fixed point in time used as a reference.
Examples
The invention of the internet marked a new epoch in the history of global communication.
Geologists study rock layers to understand each distinct epoch of the Earth's formation.