leap second

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noun

an extra second intercalated into the world's timekeeping system about once a year, made necessary by the gradual slowing down of the earth's rotation.

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Origin of leap second

First recorded in 1970–75

Words nearby leap second

leapfrog, leapfrog test, leap in the dark, leapling, leap of faith, leap second, leapt, leap year, lear, lear board, lea-rig

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

How to use leap second in a sentence

Gunshots rang out in Paris this morning on a second day of deadly violence that has stunned the French capital.
France Mourns—and Hunts|Nico Hines, Christopher Dickey|January 8, 2015|DAILY BEAST
And as he adjusted to this change in circumstances, he screamed at himself a second time: Wait!
Powerful Congressman Writes About ‘Fleshy Breasts’|Asawin Suebsaeng|January 7, 2015|DAILY BEAST
A second document was titled: “Gambia Reborn: A Charter for Transition from Dictatorship to Democracy and Development.”
The Shadowy U.S. Veteran Who Tried to Overthrow a Country|Jacob Siegel|January 6, 2015|DAILY BEAST
If 29 vote for someone else, the race for speaker goes to a second ballot for the first time in almost 100 years.
Kamikaze Congress Prepares to Strike Boehner|Ben Jacobs|January 6, 2015|DAILY BEAST

At least 29 fellow Republicans must vote against Boehner for a second ballot to be reached, and that seems very unlikely.
The YOLO Caucus' New Cry for Attention|Ben Jacobs|January 4, 2015|DAILY BEAST
In treble, second and fourth, the first change is a dodge behind; and the second time the treble leads, there's a double Bob.
Tintinnalogia, or, the Art of Ringing|Richard Duckworth and Fabian Stedman
On his head was the second-hand hat of some parvenu's coachman, gold lace, cockade and all.
The Pit Town Coronet, Volume I (of 3)|Charles James Wills
The beauty, the mystery,—this fierce sunshine or something—stir——' She hesitated for a fraction of a second.
The Wave|Algernon Blackwood
Roman Pane who accompanied Columbus on his second voyage alludes to another method of using the herb.
Tobacco; Its History, Varieties, Culture, Manufacture and Commerce|E. R. Billings.
He set down as the second the golden rule, “Whatsoever ye would that men should do unto you, do ye even so to them.”
The Giant of the North|R.M. Ballantyne

British Dictionary definitions for leap second

leap second

noun

a second added to or removed from a scale for reckoning time on one particular occasion, to synchronize it with another scale

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 leap second

leap second

[ lēp ]

A second of time, as measured by an atomic clock, added to or omitted from official timekeeping systems annually to compensate for changes in the rotation of the Earth. See more at coordinated universal time.

Cultural definitions for leap second

leap second

A second inserted into the year to make up for the fact that the Earth's rotation is slowing down.

notes for leap second

Scientists know when to insert a leap second by comparing the Earth's rotation to an atomic clock.