noun, plural e·phe·mer·i·des [ef-uh-mer-i-deez] /ˌɛf əˈmɛr ɪˌdiz/.

a table showing the positions of a heavenly body on a number of dates in a regular sequence.
an astronomical almanac containing such tables.
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
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Related Words for ephemeris

journal, calendar, yearbook, register, chronicle, annual, record, registry

Examples from the Web for ephemeris

Historical Examples of ephemeris

  • A Table of artificial numbers; to be found at the back of "Raphael's" Ephemeris.

  • Take in hand, then, the Ephemeris for the year of your birth and read this chapter with it in view.



  • And now not only is it slightly off course, but so is every ephemeris printed on Mert.

    Conquest Over Time

    Michael Shaara

  • Its position with respect to Saturn on any given date can be learned from the Ephemeris.

    Astronomy with an Opera-glass

    Garrett Putman Serviss

  • With an Ephemeris and another astrological book, I made out and copied in six hours Mdlle.

    The Memoires of Casanova, Complete

    Jacques Casanova de Seingalt

British Dictionary definitions for ephemeris


noun plural ephemerides (ˌɛfɪˈmɛrɪˌdiːz)

a table giving the future positions of a planet, comet, or satellite
an annual publication giving the positions of the sun, moon, and planets during the course of a year, information concerning eclipses, astronomical constants, etc
obsolete a diary or almanac

Word Origin for 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

Word Origin and History for ephemeris

table showing predicted positions of heavenly bodies, 1550s, Modern Latin, from Greek ephemeris "diary, calendar," from ephemeros "daily" (see ephemera). The classical plural is ephemerides.

Online Etymology Dictionary, © 2010 Douglas Harper

ephemeris in Science



Plural ephemerides (ĕf′ə-mĕrə-dēz′)

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.