The description of the word you requested from the astronomical dictionary is given below.
The sidereal time is equal to the right ascension that passes through the celestial meridian at that moment. If a given sidereal time (between 0 and 24 hours) returns, then the stars are again in the same places in the sky (seen from the same place on Earth). The sidereal time runs a little faster than ordinary time: 24 hours of sidereal time correspond to 23 hours 56 minutes 4 seconds of ordinary time. Near the equinox of september, the sidereal time and solar time are almost equal.