epoch

UK: /ˈiːpɒk/

US: /ˈɛpək; esp. Brit. ˈipɑk/

US: (ep′ək or, esp. Brit., ē′pok)

WordReference Random House Learner's Dictionary of American English © 2025

ep•och /ˈɛpək; esp. Brit. ˈipɑk/   n. [countable]

1. a period of time marked by noteworthy features or events:
   an epoch of peace.
2. Geology a division of geologic time.

ep•och•al, adj. 

WordReference Random House Unabridged Dictionary of American English © 2025

ep•och  (ep′ək or, esp. Brit., ē′pok), n. 

1. a particular period of time marked by distinctive features, events, etc.:
   The treaty ushered in an epoch of peace and good will.
2. the beginning of a distinctive period in the history of anything:
   The splitting of the atom marked an epoch in scientific discovery.
3. a point of time distinguished by a particular event or state of affairs;
   a memorable date:
   His coming of age was an epoch in his life.
4. Geology any of several divisions of a geologic period during which a geologic series is formed. Cf. age (def. 12). See table under geologic time. 
5. Astronomy
   • an arbitrarily fixed instant of time or date, usually the beginning of a century or half century, used as a reference in giving the elements of a planetary orbit or the like.
   • the mean longitude of a planet as seen from the sun at such an instant or date.
6. Physics the displacement from zero at zero time of a body undergoing simple harmonic motion.

• Greek epoché̄ pause, check, fixed time, equivalent. to ep- ep- + och- (variant stem of échein to have) + -ē noun, nominal suffix
• Neo-Latin epocha
• 1605–15

Synonyms

• 1. age, date, era, time. See age. 

Collins Concise English Dictionary © HarperCollins Publishers::

epoch / ˈiːpɒk/ noun

1. a point in time beginning a new or distinctive period
2. a long period of time marked by some predominant or typical characteristic; era
3. a precise date to which information, such as coordinates, relating to a celestial body is referred
4. a unit of geological time within a period during which a series of rocks is formed

Etymology: 17th Century: from New Latin epocha, from Greek epokhē cessation; related to ekhein to hold, have

epochal / ˈɛpˌɒk^əl/ adjective