1. (a.) Relating to the stars; astral; measure according to thestars; as, sidereal time\.

2. (a.) 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.

Cynthian anagalactic asteroidal astral astrologic astrologistic astrologous astronomic astrophysical celestial circumplanetary cislunar empyreal empyrean equinoctial extragalactic galactic heavenly heliacal intercosmic interplanetary intersidereal interstellar lunar lunary lunate lunular lunulate meteoric meteoritic nebular nebulose nebulous planetal planetarian planetary planetesimal semilunar solar sphery star-spangled star-studded starry stellar stellary terrestrial uranic zodiacal