means that which bounds in or holds in hand. The starting-point of a sequence of events harnessed together like a team of horses; also the whole period of time from one epoch to another. Our present epoch is the Birth of Christ; previous to this epoch it was the Creation of the World. In this latter sense the word is synonymous with era. (Greek, epi-echo.)
“The incarnation of Christ is the greatest moral epoch in the universe of God.” —Stevens: Parables Unfolded (“The Lost Sheep,” p. 104).
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894