Definition of H-hour in English:

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The time of day at which an attack, landing, or other military operation is scheduled to begin: they assured the Marines that at H-hour the reef would be covered by five feet of water
More example sentences
  • Preplanned raids at specific H-hours typified the 4th ID's operations.
  • H-hour of 2359 would produce maximum surprise, making it difficult for enemy forces to mobilize to repel an invasion.
  • A compromise was reached and the H-hour was changed from 1800 hours to 1405 hours on 6 October.


First World War: from H (for hour) + hour.

For editors and proofreaders

Line breaks: H-hour

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