standard time

American  

noun

1. the civil time officially adopted for a country or region, usually the civil time of some specific meridian lying within the region. The standard time zones in the United States Atlantic time, Eastern time, Central time, Mountain time, Pacific time, Yukon time, Alaska-Hawaii time, and Bering time use the civil times of the 60th, 75th, 90th, 105th, 120th, 135th, 150th, and 165th meridians respectively, the difference of time between one zone and the next being exactly one hour.

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standard time British  

noun

1. the official local time of a region or country determined by the distance from Greenwich of a line of longitude passing through the area

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standard time Scientific  

1. The time in any of the 24 time zones into which the Earth's surface is divided, usually the mean time at the central meridian of the given zone. There are four standard time zones in the contiguous continental United States: Eastern, using the 75th meridian; Central, using the 90th meridian; Mountain, using the 105th meridian; and Pacific, using the 120th meridian. Alaska Standard Time, centered on the 135th meridian, is one hour behind Pacific time, and Hawaii Standard Time, centered on the 150th meridian, is one hour behind Alaska time.

2. See more at daylight-saving time time zone

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Etymology

Origin of standard time

An Americanism dating back to 1880–85

Example Sentences

Current federal law does not permit making daylight saving permanent, but it does allow states to opt into permanent standard time — which only Arizona and Hawaii have done.

From Los Angeles Times • Mar. 7, 2026

Many see the beginning of standard time as a mild annoyance.

From Slate • Oct. 31, 2025

Most carbon removal credits have a standard time frame of 100 years, according to Erica Dorr, who leads the climate team at Riverse, a carbon crediting platform in France.

From Salon • Mar. 7, 2025

Hawaii and most of Arizona don’t make the spring switch, sticking to standard time year-round along with Puerto Rico, American Samoa, Guam and the U.S.

From Seattle Times • Mar. 7, 2024

Compare your watch with the time signals in the nearest telegraph office and find its correction referred to standard time.

From A Text-Book of Astronomy by Comstock, George C.