First Known Use: 1915
Dictionary
zero hour
zero hour
noun
: the time at which an event (such as a military attack) is scheduled to begin
Full Definition of ZERO HOUR
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
See zero hour defined for English-language learners
See zero hour defined for kids
Examples of ZERO HOUR
- <we're at the zero hour, so someone has to make a decision>
Origin of ZERO HOUR
from its being marked by the count of zero in a countdown
Related to ZERO HOUR
- Synonyms
- boiling point, breaking point, clutch, conjuncture, crisis, crossroad(s), crunch, crunch time, Dunkirk, exigency, extremity, flash point, head, juncture, tinderbox, emergency
Rhymes with ZERO HOUR
Learn More About ZERO HOUR
Browse
Next Word in the Dictionary: zeroizePrevious Word in the Dictionary: zero groupAll Words Near: zero hour
Seen & Heard
What made you want to look up zero hour? Please tell us where you read or heard it (including the quote, if possible).