(from 1928) name adopted internationally for Greenwich Mean Time (measured from Greenwich midnight), now split into several slightly different scales, one of which (UT1) is used by astronomers
Abbreviation: UT- Also called: universal coordinated time
an internationally agreed system for civil timekeeping introduced in 1960 and redefined in 1972 as an atomic timescale. Available from broadcast signals, it has a second equal to the International Atomic Time (TAI) second, the difference between UTC and TAI being an integral number of seconds with leap seconds inserted when necessary to keep it within 0.9 seconds of UT1
Abbreviation: UTC
WordReference Random House Unabridged Dictionary of American English © 2026
univer′sal time′,
- Time(often caps.) See Greenwich Time. Abbr.: UT
- 1885–90
Collins Concise English Dictionary © HarperCollins Publishers::
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