Function: noun
Date: 1764
: the interval between two successive transits of a point on the celestial sphere (as the vernal equinox) over the upper meridian of a place : 23 hours, 56 minutes, 4.1 seconds of mean time
SIDEREAL DAY
Meaning of SIDEREAL DAY in English
Merriam Webster Collegiate English Dictionary. Merriam Webster - Энциклопедический словарь английского языка. 2012