sidereal day sidereal • sidereal hour · · · Info · Definitions · Synonyms · Characters · · sidereal day · · Text Common · · Latin · · Scripts 12 · · Length 4 · · Syllables Definitions · · · (noun) the time for one complete rotation of the earth relative to a particular star, about 4 minutes shorter than a mean solar day. Synonyms: sidereal day, day. · · Noun Definition 1 Synonyms · · · day · · Synonym 1 Characters · · space U+0020 a latin small letter a U+0061 d latin small letter d U+0064 e latin small letter e U+0065 i latin small letter i U+0069 l latin small letter l U+006C r latin small letter r U+0072 s latin small letter s U+0073 y latin small letter y U+0079