Julian day

noun

A date expressed as a real number of days counted with GMT noon on 1 January 4713 BCE in proleptic Julian calendar (November 24, 4714 BCE, in the proleptic Gregorian calendar) as zero; used primarily by astronomers and historians to compare events recorded in different cultures.

Similar
JDJulian date
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Meanings

nounJulian day (plural Julian days)

plural Julian days

  1. A date expressed as a real number of days counted with GMT noon on 1 January 4713 BCE in proleptic Julian calendar (November 24, 4714 BCE, in the proleptic Gregorian calendar) as zero; used primarily by astronomers and historians to compare events recorded in different cultures.

    Synonyms: JD, Julian date

Synonyms & antonyms

nounA date expressed as a real number of days counted with GMT noon on 1 January 4713 BCE in proleptic Julian calendar (November 24, 4714 BCE, in the proleptic Gregorian calendar) as zero; used primarily by astronomers and historians to compare events recorded in different cultures.

Similar
JDJulian date
Also see
julian date

Translations

Finnish juliaaninen päivä
  • juliaaninen päivädate
Irish lá Iúlach
  • lá Iúlachdate
Cite this entry
APA

Julian day. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/Julian%20day

MLA

“Julian day.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/Julian%20day. Accessed November 4, 2026.

Chicago

WatkinsX Dictionary, s.v. “Julian day,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/Julian%20day.

Source: Julian day on Wiktionary, CC BY-SA 4.0.