zero hour

noun

Definition of zero hour

  1. 1a :  the hour at which a planned military operation is scheduled to startb :  the time at which a usually significant or notable event is scheduled to take place

  2. 2 :  a time when a vital decision or decisive change must be made

Examples of zero hour in a Sentence

  1. we're at the zero hour, so someone has to make a decision

Origin and Etymology of zero hour

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


ZERO HOUR Defined for English Language Learners

zero hour

noun

Definition of zero hour for English Language Learners

  • : the time at which an event (such as a military attack) is scheduled to begin



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marked by lack of plan or order

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