• synonyms

zero hour

See more synonyms for zero hour on Thesaurus.com
  1. the time set for the beginning of a military attack or operation.
  2. the time set for the beginning of any event or action.
  3. a decisive or critical time.
Show More

Origin of zero hour

First recorded in 1915–20
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words


British Dictionary definitions for zero hour

zero hour

  1. military the time set for the start of an attack or the initial stage of an operation
  2. informal a critical time, esp at the commencement of an action
Show More
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