zero hour
4
5.1
- noun
- /ˈziːroʊ ˈaʊər/
:
hora cero
- As the clock struck midnight, zero hour arrived, signaling the start of the New Year celebrations.
- minutes until zero hour
Examples
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Cleared for launch at zero hour, 9 a.m.
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Zero hour will be 6:10.
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How much time till zero hour?
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The zero hour of the second front.
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We are nearly at zero hour, so do not lose heart.
Fiction book (2002) -
65 minutes till zero hour.
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Zero hour is upon us.
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That night, the troops gathered around their campfires, awaiting zero hour ...
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Zero hour, 9:00 a.m.
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The team prepared all week for zero hour, the moment they would begin their mission.
Synonyms
2
1.8
The planned time when something begins
How Much Notice
Surface Forms
Morphology
The meaning 'the exact time set for the start of a planned operation' is directly derivable from combining 'zero' (starting/reference point) with 'hour' (time), so a learner who knows both constituents can infer a start time. This compositional logic is cross-linguistically plausible and follows normal noun‑compounding patterns, making the expression predictable for B1 learners.
Etymology
Zero hour comes from old army plans where commanders wrote zero next to a time so everyone knew the exact hour to begin an attack. That's why today zero hour means 'the exact time' something will start.