Definition

1. Noun:
   • The precise time at which a planned action or operation is scheduled to begin: This term originates from military usage, referring to the specific moment an attack or mission commences. It implies a critical, fixed point in time from which subsequent events are measured.

Usage Examples

• Noun:
  • The commander announced that zero hour for the offensive would be at 0500 hours.
  • For the project launch, zero hour is set for 9:00 AM tomorrow.

Advanced Usage

• "At zero hour": At the exact moment something begins.
  • The troops moved out at zero hour.
• "Approaching zero hour": The period just before a critical event starts.
  • Tension was high in the control room as they were approaching zero hour for the rocket launch.

Variants and Related Words

• H-hour (n): A synonymous military term for the specific hour an operation begins.
• D-day (n): The designated day on which an operation initiates, often used in conjunction with "zero hour" or "H-hour" to specify the exact time.

Synonyms

• Start time: The time at which something begins.
• Kickoff: The start of an event or activity.
• Commencement: The beginning of something.

Related Phrases

• Countdown to zero hour: The final period of waiting and preparation before an event starts.
  • The team began the countdown to zero hour for the software update.

Related Idioms

• The zero hour: Used to emphasize the critical nature of the starting moment.
  • Everything must be ready by the zero hour; there will be no second chances.

Noun

1. the time set for the start of an action or operation