sidereal day
noun
,
Astronomy
1.
the interval between two successive passages of the vernal equinox over the meridian, being about four minutes shorter than a mean solar day.
Origin
1785-95
Examples from the web for
sidereal day
Beginning of a
sidereal day
at a given place occurs at the instant the vernal equinox is at upper transit.
British Dictionary definitions for
sidereal day
sidereal day
noun
1.
See
day
(sense 5)