leap second


Definition of leap second

: an intercalary second added to Coordinated Universal Time to compensate for the slowing of the earth's rotation and keep Coordinated Universal Time in synchrony with solar time

Examples of leap second in a Sentence

Recent Examples on the Web Because Earth is now rotating faster, a leap second would need to be taken away to catch our timekeeping up with Earth's increasing rotational speed, McCarthy said. Megan Marples, CNN, 8 Aug. 2022 Leap seconds have been added in the past – the first leap second was added was in 1972, and they're typically added in June or December. Sarah Raza, USA TODAY, 5 Aug. 2022 With the reversal of that trend in the past years, the last time a positive leap second was added was on the last day of 2016. Christine Mui, Fortune, 4 Aug. 2022 As opposed to leap years, which have an extra day added, a negative leap second would mean clocks skip one second. Caitlin O'kane, CBS News, 3 Aug. 2022 Leap seconds have been added in the past; first leap second was added was in 1972, and they're typically added in June or December. Sarah Raza, Detroit Free Press, 3 Aug. 2022 The first leap second was added back in 1972, with 26 more being added throughout the last several decades. Joshua Hawkins, BGR, 2 Aug. 2022 This minuscule change in time could introduce the need for a negative leap second. Tim Newcomb, Popular Mechanics, 1 Aug. 2022 After an initial insertion of 10 leap seconds in 1972, timekeepers now add a leap second to atomic time roughly every year and a half. New York Times, 25 Apr. 2022 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'leap second.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of leap second

1971, in the meaning defined above

Learn More About leap second

Time Traveler for leap second

Time Traveler

The first known use of leap second was in 1971

See more words from the same year

Dictionary Entries Near leap second

leap out at

leap second

leap/spring/swing into action

See More Nearby Entries 

Statistics for leap second

Last Updated

11 Aug 2022

Cite this Entry

“Leap second.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/leap%20second. Accessed 15 Aug. 2022.

Style: MLA
MLACheck Mark Icon ChicagoCheck Mark Icon APACheck Mark Icon Merriam-WebsterCheck Mark Icon


Test Your Vocabulary

Challenging Words You Should Know

  • hedgehog reading a book
  • Often used to describe “the march of time,” what does inexorable mean?
Spell It

Can you spell these 10 commonly misspelled words?

Universal Daily Crossword

A daily challenge for crossword fanatics.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!