sidereal(redirected from Siderial)
Also found in: Dictionary, Thesaurus, Legal.
1. of, relating to, or involving the stars
2. determined with reference to one or more stars
sidereal(sÿ-deer -ee-ăl) Relating to or measured or determined with reference to the stars.
Referring to a quantity, such as time, to indicate that it is measured in relation to the apparent motion or position of the stars.
Of or pertaining to the stars. Although sidereal generally refers to the stars and tropical to the vernal equinox, sidereal time and the sidereal day are based upon the position of the vernal equinox relative to the meridian. The sidereal year is based upon the stars.