Ĕp'och or Ĕp'o-chē, n.

(Synop., § 130), n. [Gr. ἐποχή, a check, hindrance, pause, stop, in the reckoning of time, from ἐπέχειν, to have or hold on, to keep in, hold back, check, stop, from ἐπί and ἔχειν, to have, hold; L. Lat. epocha, Fr. époque.]

1Sense 1. A fixed point of time, from which succeeding years are numbered; a period of time, longer or shorter, remarkable for events of great subsequent influence. “An epoch in the history of astronomy.” Whewell. “Great epochs and crises in the kingdom of God.” Trench.

2Sense 2. (Astron.) (a.) The date at which a planet or comet has a given longitude or position. (b.) An arbitrary fixed date, for which the elements used in computing the place of a planet, or other heavenly body, at any other date, are given; as, the epoch of Mars; lunar elements for the epoch March 1st, 1860.

Synonyms—Era; time; date; period; age. See ERA.

—EPOCH, ERA. These two words have been greatly interchanged, but are now undergoing a separation which may thus be stated: Epoch denotes a period in the progress of events when some important occurrence takes place. Thus we speak of the Christian epoch, or period of Christ's coming into the world; we speak of the epoch of the Reformation, the epoch of maritime discovery, &c. An era is a point from which chronologers reckon their dates. It is usually (but not always) some epoch; as, the Christian era, the Mohammedan era, &c. Hence, era is applied in a secondary sense to those epochs which become the starting-points of subsequent events, though not of chronology. Thus, we speak of the era of the Reformation, when we think of it as opening the way for a new series of events; of the eras in geology, &c. Had we been thinking simply of the time at which these events took place, we should have called them epochs.