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ephemeris time

noun

: a uniform measure of time defined by the orbital motions of the planets

Word History

First Known Use

1950, in the meaning defined above

Time Traveler
The first known use of ephemeris time was in 1950

Rhymes for ephemeris time

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ephemeris
ephemeris time
ephemeron
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Cite this Entry

“Ephemeris time.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ephemeris%20time. Accessed 29 Nov. 2025.

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Britannica.com: Encyclopedia article about ephemeris time

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