: the mean time that is associated with the prime meridian of Greenwich, England, and historically used as the prime basis of standard time throughout the world
The British traditionally used Greenwich Mean Time, calculated from the meridian running through Greenwich, a borough of London.—
The New York Times
The New York TimesCoordinated Universal Time is what used to be called Greenwich Mean Time, but the new name doesn't make it any more universal than it ever was, and it remains a time zone centered in Britain.—Natalie Angier
—abbreviation GMT
Natalie Angiercalled also Greenwich Time
compare coordinated universal timeExamples of Greenwich Mean Time in a Sentence
Recent Examples on the Web
The lunar eclipse occurs on 25th March at 7 a.m. Greenwich Mean Time.
—Lisa Stardust, refinery29.com, 22 Mar. 2024
This was a problem as the ship moved its clock ahead an hour on four separate days to adjust to the five-hour time difference between Eastern time in New York and Greenwich Mean Time in London.
—Elizabeth Weise, USA TODAY, 18 Jan. 2024
Here's the catch, though: Amazon will drop each episode at midnight in Greenwich Mean Time (GMT), according to Decider.
—Olivia Evans, Women's Health, 1 Sep. 2023
The dial of the Aqua Terra titanium version renders the continents in black and gray on a titanium surface—which, like the others, is done with laser ablation—with the red London city colored by red varnish to highlight the location of Greenwich Mean Time (GMT).
—Carol Besler, Robb Report, 17 May 2023
Note: Dates are based on Greenwich Mean Time.
—Lynsey Chutel, New York Times, 9 Mar. 2023
Sailors used them to determine longitude by comparing Greenwich Mean Time and the time at the current location by reading the night sky.
—Carol Besler, Robb Report, 1 Mar. 2023
Pacific Time, Eastern Time, Greenwich Mean Time — and one day, perhaps, Moon Time?
—Denise Chow, NBC News, 27 Feb. 2023
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Lisa Stardust, refinery29.com, 22 Mar. 2024
This was a problem as the ship moved its clock ahead an hour on four separate days to adjust to the five-hour time difference between Eastern time in New York and Greenwich Mean Time in London.
—Elizabeth Weise, USA TODAY, 18 Jan. 2024
Here's the catch, though: Amazon will drop each episode at midnight in Greenwich Mean Time (GMT), according to Decider.
—Olivia Evans, Women's Health, 1 Sep. 2023
The dial of the Aqua Terra titanium version renders the continents in black and gray on a titanium surface—which, like the others, is done with laser ablation—with the red London city colored by red varnish to highlight the location of Greenwich Mean Time (GMT).
—Carol Besler, Robb Report, 17 May 2023
Note: Dates are based on Greenwich Mean Time.
—Lynsey Chutel, New York Times, 9 Mar. 2023
Sailors used them to determine longitude by comparing Greenwich Mean Time and the time at the current location by reading the night sky.
—Carol Besler, Robb Report, 1 Mar. 2023
Pacific Time, Eastern Time, Greenwich Mean Time — and one day, perhaps, Moon Time?
—Denise Chow, NBC News, 27 Feb. 2023
Dictionary Entries Near Greenwich Mean Time
Cite this Entry
“Greenwich Mean Time.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/Greenwich%20Mean%20Time. Accessed 29 Nov. 2024.
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Greenwich mean time
noun
Green·wich mean time
ˈgrin-ij- 
ˈgren-,
-ich-
: the time of the meridian of Greenwich used as the basis of standard time throughout the world
called also Greenwich time
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