sidereal

[ sahy-deer-ee-uhl ]

adjective

, Astronomy.

1. determined by or from the stars:

   sidereal time.

2. of or relating to the stars.

sidereal

/ saɪˈdɪərɪəl /

adjective

1. of, relating to, or involving the stars
2. determined with reference to one or more stars

   the sidereal day

sidereal

/ sī-dîr′ē-əl /

1. Relating to the stars or constellations.
2. Measured with respect to the background of fixed stars instead of the Sun.

Derived Forms

• siˈdereally, adverb

Other Words From

• si·dere·al·ly adverb
• nonsi·dere·al adjective
• unsi·dere·al adjective

Word History and Origins

Origin of sidereal¹

1625–35; < Latin sīdere ( us ) of, belonging to the stars ( sīder-, stem of sīdus star, constellation + -eus adj. suffix) + -al ¹

Word History and Origins

Origin of sidereal¹

C17: from Latin sīdereus, from sīdus a star, a constellation

Example Sentences

That’s where Mercer’s triumph manifests itself, there at the end of the great sidereal cycle.

From Literature

Note: For simplicity’s sake, these are all sidereal days, and “day” refers to an Earth day.

From The Verge

It's that time of the sidereal year where we take stock of what's been going on during the last orbit of Earth around the Sun.

From Scientific American

But one puzzling signal showed up most days at the same sidereal time.

From Scientific American

Mr Beck, Rocket Lab’s wise man, has taken it upon himself to create his own sidereal epiphany.

From The Guardian

Related Words

• glittering
• luminous
• sparkling
• stellar