zero hour

• Momento crítico fijado para el comienzo de una operación, acción o evento importante, especialmente en contexto militar o de planes coordinados; la hora cero en la que algo decisivo está programado para iniciarse.

The critical moment when an important event, operation, or decision is scheduled to begin; the time set for the start of a planned action.

1. Critical momentB2formal

   The time when an important event or action is scheduled to begin; the decisive moment.

   hora cero

   • Zero hour for the attack was set at dawn.
   • The team waited nervously for zero hour to launch the product.
   • At zero hour, the countdown began for the rocket launch.

2. Military operation startC1formal

   The exact time designated for the start of a military operation.

   hora cero (militar)

   • The general ordered the troops to be ready by zero hour.
   • Zero hour was postponed due to bad weather conditions.
   • All units must be in position before zero hour.