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epoch

 - 4 dictionary results

ep⋅och

  [ep-uhk or, especially Brit., ee-pok]
Use epoch in a Sentence
–noun
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. Compare age (def. 12).
5. Astronomy.
a. 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.
b. 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.
Origin:
1605–15; < NL epocha < Gk epoch pause, check, fixed time, equiv. to ep- ep- + och- (var. s. of échein to have) + -ē n. suffix

Synonyms:
1. age, date, era, time. See age.
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
Cite This Source Link To epoch
ep·och   (ěp'ək, ē'pŏk')   
n.  

    1. A particular period of history, especially one considered remarkable or noteworthy.

    2. A notable event that marks the beginning of such a period. See Synonyms at period.

  2. A unit of geologic time that is a division of a period.

  3. Astronomy An instant in time that is arbitrarily selected as a point of reference.


[Medieval Latin epocha, measure of time, from Greek epokhē, a point in time; see segh- in Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Word Origin & History

epoch 
1614, "point marking the start of a new period in time" (e.g. the founding of Rome, the birth of Christ, the Hegira), from M.L. epocha, from Gk. epokhe "stoppage, fixed point of time," from epekhein "to pause, take up a position," from epi- "on" + ekhein "to hold." Transf. sense of "a period of time" is c.1628; geological usage (not a precise measurement) is from 1802.
Online Etymology Dictionary, © 2001 Douglas Harper
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Computing Dictionary

epoch
1. (Probably from astronomical timekeeping) A term used originally in Unix documentation for the time and date corresponding to zero in an operating system's clock and timestamp values.
Under most Unix versions the epoch is 1970-01-01 00:00:00 GMT; under VMS, it's 1858-11-17 00:00:00 (the base date of the US Naval Observatory's ephemerides); on a Macintosh, it's 1904-01-01 00:00:00.
System time is measured in seconds or ticks past the epoch. Weird problems may ensue when the clock wraps around (see wrap around), which is not necessarily a rare event; on systems counting 10 ticks per second, a signed 32-bit count of ticks is good only for 0.1 * 2**31-1 seconds, or 6.8 years. The one-tick-per-second clock of Unix is good only until 2038-01-18, assuming at least some software continues to consider it signed and that word lengths don't increase by then. See also wall time.
2. (Epoch) A version of GNU Emacs for the X Window System from NCSA.
[The Jargon File]
(2004-06-10)

The Free On-line Dictionary of Computing, © 1993-2007 Denis Howe
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