WordNet (r) 3.0 (2006):

time zone
    n 1: any of the 24 regions of the globe (loosely divided by
         longitude) throughout which the same standard time is used

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "time zone":
   Alaska time, Atlantic time, Central time, Eastern time, GMT,
   Greenwich mean time, Greenwich time, Mountain time, Yukon time,
   apparent time, civil time, daylight-saving time, fast time,
   local time, mean solar time, mean time, sidereal time, slow time,
   solar time, standard time, summer time, zone time



The Free On-line Dictionary of Computing (30 December 2018):

time zone

   One of approximately 24 longitudinal divisions of the globe,
   nominally 15 degrees wide, in which clocks show the same time.
   Some zones follow the boundaries of states or territories,
   others differ from neighbouring zones by more or less than one
   hour.

   Computers can be programmed to take into account the time zone
   each user is working in, which is not necessarily the same as
   the zone the computer is in.

   See also TZ.

   (1997-07-20)