leap second

noun

Updated on: 5 May 2018

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

Recent Examples of leap second from the Web

That all seems to make sense, but some people are majorly freaking out about the leap second, because messing with time has historically wreaked havoc on our technology-dependent world.

— noelle devoe, Seventeen, "Beware the Leap Second: Will Today's Extra Second Break The Internet?!," 30 June 2015
But unlike leap years, leap seconds are not predictable in advance.

— jay bennett, Popular Mechanics, "The Centuries-Long Quest to Measure One Second," 24 Mar. 2017
The phenomenon of the leap second, which is designed to control for unpredictable variations in the Earth's rotation.

— eric limer, Popular Mechanics, "There's a New Unit of Time Just for Virtual Reality," 24 Jan. 2018
Felix Pena then walked Zack Cozart before Votto lined an RBI single off the glove of leaping second baseman La Stella, making it 4-2.

— USA TODAY, "Happ hits 3-run homer in 8th, Cubs beat Reds 5-4," 29 Sep. 2017

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.