Meanings
nounsidereal day (plural sidereal days)
plural sidereal days
- astronomyOne day of sidereal time; the time in which Earth rotates once around its axis, relative to the point of the vernal equinox (about 23 hours, 56 minutes, 4 seconds).
- astronomyThe rotational period of Earth; the time in which Earth rotates around its axis 360 degrees.
Synonyms & antonyms
nounthe time for one complete rotation of the earth relative to a particular star, about 4 minutes shorter than a mean solar day
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Also see
Synonym sets from Open English WordNet, CC BY 4.0.
Translations
Chinese Mandarin 恆星日 /恒星日
- 恆星日 /恒星日 (héngxīngrì)day of sidereal time
Dutch siderische dag
- siderische dagday of sidereal time
Finnish sideerinen vuorokausi
- sideerinen vuorokausiday of sidereal time
French jour sidéral
- jour sidéralday of sidereal time
German siderischer Tag, Sterntag
- siderischer Tagday of sidereal time
- Sterntagday of sidereal time
Japanese 恒星日
- 恒星日 (kōseijitsu)day of sidereal time
Romanian zi siderală
- zi sideralăday of sidereal time
Russian звёздные су́тки
- звёздные су́тки (zvjózdnyje sútki)day of sidereal time
Cite this entry
APA
sidereal day. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/sidereal%20day
MLA
“sidereal day.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/sidereal%20day. Accessed November 4, 2026.
Chicago
WatkinsX Dictionary, s.v. “sidereal day,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/sidereal%20day.
Source: sidereal day on Wiktionary, CC BY-SA 4.0.