sidereal
UK /saɪˈdɪə.ɹi.əl/ · US /saɪˈdɪɚ.i.əl/ adjective
Forms sideral sidaereal
- adjective Of or relating to the stars.
- adjective (astronomy) Relating to a measurement of time relative to the position of the stars.
- adjective (astronomy) Relating to a measurement of time relative to the point of the vernal equinox.
Antonyms
Etymology
From Latin sīdereus + -al (cf. Latin sīderālis), from sīdus (“star, constellation”), of unknown ultimate origin, likely a substrate language such as Pre-Greek.
Webster’s 1913
- adjective Relating to the stars; starry; astral; as, sidereal astronomy.
- adjective Measuring by the apparent motion of the stars; designated, marked out, or accompanied, by a return to the same position in respect to the stars; as, the sidereal revolution of a planet; a sidereal day. Sidereal clock, day, month, year. See under Clock, Day, etc. -- Sideral time, time as reckoned by sideral days, or, taking the sidereal day as the unit, the time elapsed since a transit of the vernal equinox, reckoned in parts of a sidereal day. This is, strictly, apparent sidereal time, mean sidereal time being reckoned from the transit, not of the true, but of the mean, equinoctial point.
Etymology [L. sidereus, from sidus, sideris, a constellation, a star. Cf. Sideral, Consider, Desire.]
Sources: Wiktionary · WordNet 3.0 · Webster’s 1913 — from the Wiktionary entry “sidereal”, CC BY-SA 4.0. Details