[ ih-fem-er-is ]
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noun,plural e·phe·mer·i·des [ef-uh-mer-i-deez]. /ˌɛf əˈmɛr ɪˌdiz/.
  1. a table showing the positions of a heavenly body on a number of dates in a regular sequence.

  2. an astronomical almanac containing such tables.

  1. Archaic. an almanac or calendar.

Origin of ephemeris

1545–55; <Latin ephēmeris day book, diary <Greek ephēmerís diary, account book, derivative of ephḗmeros;see ephemeral

Words Nearby ephemeris

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British Dictionary definitions for ephemeris


/ (ɪˈfɛmərɪs) /

nounplural ephemerides (ˌɛfɪˈmɛrɪˌdiːz)
  1. a table giving the future positions of a planet, comet, or satellite

  2. an annual publication giving the positions of the sun, moon, and planets during the course of a year, information concerning eclipses, astronomical constants, etc

  1. obsolete a diary or almanac

Origin of ephemeris

C16: from Latin, from Greek: diary, journal; see ephemeral

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for ephemeris


[ ĭ-fĕmər-ĭs ]

Plural ephemerides (ĕf′ə-mĕrə-dēz′)
  1. A table giving the coordinates of a celestial body at specific times during a given period. Ephemerides can be used by navigators to determine their longitude while at sea and by astronomers in following objects such as comets. The use of computers has allowed modern ephemerides to determine celestial positions with far greater accuracy than in earlier publications.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.