Question

What is d definition of standard time?

Answer 1

Standard time is the synchronization of clocks within a geographical area or region to a single time standard, rather than using solar time or a locally chosen meridian (longitude) to establish a local mean time standard.

Answer 2

the time of a region or country that is established by law or general usage as civil time; specifically : the mean timeof a meridian that is a multiple of 15 arbitrarily applied to a local area or to one of the 24 time zones and designated as a number of hours earlier or later than Greenwich meantime.