Epoch
in ordinary language, a point of time from which a new computation of years is begun. Technical uses:
History. A point of time in which an event of such importance takes place that its influence is powerfully felt in all succeeding time. Geology. The term is sometimes used for period, as the Tertiary epoch; this sense of the word is loose and objectionable, as the term epoch more properly refers to the moment at which a new space of time commences than to its whole duration.
Astronomy. The longitude which a planet has at any given moment of time.
To predict this for any future period the longitude at a certain instant in the past must be known; that instant is the epoch of the planet, which is an abbreviation for its longitude at that epoch.
EPWORTH LEAGUE An epoch and an era are different.
Both mark important events, but an era is an epoch which is chronologically dated from; an epoch is not marked in this way. The birth of Christ and the Reformation were both of them highly important epochs in the history of mankind; the former, the inconceivably greater event of the two, gave rise to the Christian era; but the Protestant nations and Churches do not any of them reckon time from the Reformation. The birth of Christ was, therefore, both an epoch and an era, the Reformation an epoch only.