|Noun||1.||Greenwich Mean Time - the local time at the 0 meridian passing through Greenwich, England; it is the same everywhere|
|(time, standard)||Greenwich Mean Time - (GMT) The local time on the Greenwich
meridian, based on the hypothetical mean sun (which averages
out the effects of the Earth's elliptical orbit and its tilted
axis). GMT is the basis of the civil time for the UK.|
In 1925 the reference point was changed from noon to midnight and it was recommended that the term "Universal Time" should be used for the new GMT.
Authorities disagreed on whether GMT equates with UT0 or UT1, however the differences between the two are of the order of thousandths of a second. GMT is no longer used for scientific purposes.