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ephemeris

[ ih-fem-er-is ]
/ ɪˈfɛm ər ɪs /
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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.

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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. 2021

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British Dictionary definitions for ephemeris

ephemeris
/ (ɪˈfɛmərɪs) /

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

Scientific definitions for ephemeris

ephemeris
[ ĭ-fĕmər-ĭs ]

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.
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