daylight-saving time

or day·light-sav·ings time

[ dey-lahyt-sey-ving ]
/ ˈdeɪˌlaɪtˈseɪ vɪŋ /
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the civil time observed when daylight saving is adopted in a country or community.
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Origin of daylight-saving time

First recorded in 1905–10

Words nearby daylight-saving time

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


What is daylight-saving time?

Daylight-saving time is the period during which the time is adjusted in order to gain an extra hour of daylight in the evening during part of the year.

Daylight-saving time begins in the spring, when clocks are set one hour ahead. They are then set one hour back in the fall. Daylight-saving time is also commonly called daylight-savings time. It’s abbreviated DST.

The term daylight saving (or daylight savings) refers to the practice of adjusting the time in this way. Both of these terms can be used as short forms of daylight-saving time. All of these terms can also refer to the specific mode of time that’s being used during a particular period, as opposed to standard time.

People often use the simple mnemonic spring forward, fall back to remember to set clocks forward one hour (e.g., from 2 a.m. to 3 a.m.) in the spring and backward one hour (e.g., from 2 a.m. to 1 a.m.) in the fall. This is often seen as resulting in one less hour of sleep time on the day that the clocks are adjusted in the spring and one more hour when they’re changed in the fall.

Daylight-saving time is widespread, but it is not observed everywhere or in the same way in all locations. In the U.S., for example, daylight-saving time is not observed by the states of Arizona or Hawaii.

Example: Don’t forget to set your clocks ahead for daylight-saving time.

When is daylight-saving time?

The specific dates on which daylight-saving time begins and ends change from year to year, but they are always scheduled for the early morning hours of a Sunday.

The dates for the beginning and end of daylight-saving time also vary from place to place within a given year.

In the U.S., daylight-saving time in 2021 will begin on March 14 and end on November 7. In 2022, it will begin on March 13 and end on November 6.

In the U.K., daylight-saving time in 2021 will begin on March 28 and end on October 31. In 2022, it will begin on March 27 and end on October 30.

More information and context on daylight-saving time

The first records of the term daylight-saving time come from the early 1900s. The practice is thought to have been first proposed by U.S. statesman and scientist Benjamin Franklin in the 1700s. The idea gained traction in the late 1800s and was first officially adopted by Germany in 1916, followed soon after by several other countries, including the U.S. in 1918. Daylight-saving time was enacted during this time in part as a way to save energy costs during World War I, and the same thing was done during World War II. An annual period of daylight-saving time was permanently enacted for much of the U.S. in 1973.

Today, the need for daylight-saving time is debated, with critics noting that it no longer serves the practical purposes that it was once intended to.

What are some terms that often get used in discussing daylight-saving time?

How is daylight-saving time discussed in real life?

Daylight-saving time is commonly called daylight-savings time or called daylight saving or daylight savings for short (though those two terms are also used to refer to the practice of adjusting the time). Most people look forward to more daylight, but not losing an hour of sleep when “springing forward.”

Try using daylight-saving time!

True or False?

All locations around the world observe daylight-saving time in the same way.

How to use daylight-saving time in a sentence

British Dictionary definitions for daylight-saving time

daylight-saving time

time set usually one hour ahead of the local standard time, widely adopted in the summer to provide extra daylight in the eveningAlso called (in the US): daylight time See also British Summer Time
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for daylight-saving time

daylight-saving time
[ dā′līt-sāvĭng ]
daylight-savings time

Time during which clocks are set one hour or more ahead of standard time to provide more daylight at the end of the working day during late spring, summer, and early fall. First proposed by Benjamin Franklin, daylight saving time was instituted in various countries during both world wars in the 20th century and was made permanent in most of the United States beginning in 1973. Arizona, Hawaii, most of eastern Indiana, and certain US territories and possessions do not observe daylight saving time.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.