zero hour

noun

1
a
: the hour at which a planned military operation is scheduled to start
b
: the time at which a usually significant or notable event is scheduled to take place
2
: 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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The King video marked the zero hour for new forms of activism using cameras. Will Potter july 7, Literary Hub, 7 July 2025 She's stopped, however, when Derringer and Clarke burst in at the zero hour, giving impassioned speeches about the importance of the alliance. Randall Colburn, EW.com, 3 July 2025 Fighting, however, continued up to the zero hour, with Israeli airstrikes in Lebanon far into the night. Scott Neuman, NPR, 27 Nov. 2024 English learners can attend a specialized class for learning to speak and write can be accomplished with a before-school (zero hour) or after-school period. Madeleine Parrish, The Arizona Republic, 8 Oct. 2024 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, baltimoresun.com/maryland/carroll, 6 Mar. 2021 As Pac-12 teams prepare for Week Two, the existential clock approaches zero hour. oregonlive, 8 Sep. 2022

Word History

Etymology

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

Browse Nearby Words

Cite this Entry

“Zero hour.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/zero%20hour. Accessed 12 Jul. 2025.

Kids Definition

zero hour

noun
1
: the hour at which a military action is scheduled to start
2
: a moment of crisis
Last Updated: - Updated example sentences
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