zero hour


: the hour at which a planned military operation is scheduled to start
: the time at which a usually significant or notable event is scheduled to take place
: a time when a vital decision or decisive change must be made

Examples of zero hour in a Sentence

we're at the zero hour, so someone has to make a decision
Recent Examples on the Web As the zero hour approached, the men fiddled with their automatic rifles while their leader, Habib Rahman Inqayad, scrambled to get the exact location of their target. Safiullah Padshah, New York Times, 17 June 2023 The Germans called 1945 Stunde null, zero hour. The New Yorker, 4 July 2021 This point of the Vernal Equinox on the celestial equator defines the zero hour of R.A. in our coordinate system. Curtis Roelle,, 6 Mar. 2021 As Pac-12 teams prepare for Week Two, the existential clock approaches zero hour. oregonlive, 8 Sep. 2022 Hiking through the emerald green canopy of the bosque, or riverside cottonwood forest, near downtown Albuquerque, Tricia Snyder, an advocate for WildEarth Guardians, believes zero hour has arrived for the Rio Grande. Jim Robbins, Wired, 25 June 2022 Biden's August deadline marks zero hour for the next phase of a larger international quest: to trace back the virus in order to hold the responsible parties to account, and to understand its inception in order to prevent the next one. Sasha Pezenik, ABC News, 25 Aug. 2021 In Germany, some 3 million workers are being supported, with the government paying up to 60% of their net salary if they are temporarily put on shorter or zero hours. Masha MacPherson and David McHugh, The Christian Science Monitor, 30 Apr. 2020 Major milestones in the emergency plan are performed according to a predetermined schedule in the hours and days leading up to the zero hour. Daniel B. Hess, CNN, 2 Sep. 2019 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'zero hour.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


from its being marked by the count of zero in a countdown

First Known Use

1915, in the meaning defined at sense 1a

Time Traveler
The first known use of zero hour was in 1915

Dictionary Entries Near zero hour

Cite this Entry

“Zero hour.” Dictionary, Merriam-Webster, Accessed 2 Oct. 2023.

Kids Definition

zero hour

: the hour at which a military action is scheduled to start
: a moment of crisis
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