si·​de·​re·​al sī-ˈdir-ē-əl How to pronounce sidereal (audio)
: of, relating to, or expressed in relation to stars or constellations : astral

Examples of sidereal in a Sentence

Recent Examples on the Web Called sidereal time, the measurement calculates the length of a day by comparing the earth's rotation to the stars. Aaron Pressman, Fortune, 12 Apr. 2017 One tweet, in particular, has birthed a fair number of inky astronauts floating across a sidereal arm. Jesse Lichtenstein, New York Times, 15 June 2017 With this definition, a sidereal year is something like 365.256363 solar days. Rhett Allain, WIRED, 29 Feb. 2012

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'sidereal.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Latin sidereus, from sider-, sidus star, constellation

First Known Use

1612, in the meaning defined above

Time Traveler
The first known use of sidereal was in 1612


Dictionary Entries Near sidereal

Cite this Entry

“Sidereal.” Dictionary, Merriam-Webster, Accessed 21 Apr. 2024.

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