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.

---

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

---

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

---

Etymology

Origin of standard time

An Americanism dating back to 1880–85

Example Sentences

In 2018, California voters approved Proposition 7, which would allow the state Legislature to approve either permanent daylight saving time or permanent standard time — eliminating the annual time shifts — with a two-thirds vote.

From Los Angeles Times • Nov. 1, 2025

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

As a refresher: Each year in the United States, we spring forward an hour in March, and then go back to standard time in November.

From New York Times • Mar. 7, 2024

Standard Time.—The standard time adopted in Egypt is that of the longitude of Alexandria, 30� E., i.e. two hours earlier than Greenwich time.

From Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 1 "Edwardes" to "Ehrenbreitstein" by Various