An Age.
This was a distinct period of time. Or so everyone thought as such, for the average definition of the term itself.
But for beings on the path of power, especially those from the third League and above, an Age was something different altogether.
An Age usually implies a considerable extent of time, especially one associated with a dominant personality, influence, characteristic, or institution.
The Age of Ragnarok for example.
This was an extended period of time, with the dominant personality of "Doom of the Gods". It's influence was to spread the idea of eliminating all the "Gods", and its characteristics was literally to bring calamity onto the "Gods".
This was an Age.
It had its own purpose, and definition.
But most importantly, there could be plenty of such Ages, collinear to one another on the same path, as they created a pattern that took one from a certain beginning, to a certain end.
For example, there was;
