A solar day is defined by the Sun's return to the local meridian, while a sidereal day is defined by the return of the March equinox to the local meridian. A solar day is approximately 3 minutes and ...

About time keeping, the definition of “sidereal” is “of or with respect to the distant stars (i.e. the constellations or the fixed stars, not the sun or planets)”, as defined after a google search.