Definition

1. Noun:
   • A 24-hour period reckoned from midnight to midnight: A "civil day" is the standard unit of time measurement used in everyday life, calendars, and civil affairs, beginning and ending at midnight (00:00). This contrasts with other types of days, such as an astronomical day.

Usage

• The term is used in formal, technical, or legal contexts to specify the precise definition of a "day" for scheduling, contracts, or scientific distinction.
• It is the conventional day used by society.

Examples

• Noun:
  • According to the contract, payment is due within 30 civil days.
  • The astronomical day and the civil day do not exactly coincide.
  • Most countries use the civil day for their official timekeeping.

Advanced Usage

• "Mean civil day": Refers to the average length of the civil day over a year, accounting for the slight variations in the solar day.
• The concept is fundamental in time zone definitions, where each zone is defined by an offset from Coordinated Universal Time (UTC) for its local civil day.

Variants and Related Words

• Solar day: The time between two successive transits of the Sun over a given meridian, which is slightly variable and differs from the standardized civil day.
• Calendar day: Often used synonymously with "civil day" to mean a full day on the calendar.
• 24-hour period: A more general descriptive term.

Synonyms

• Calendar day
• 24-hour day

Notes on Meaning

• The primary meaning is the standard day from midnight to midnight. It is defined to provide a uniform basis for civil timekeeping, as opposed to days measured from noon (like some historical astronomical days) or days based on other celestial cycles.

Noun

1. a day reckoned from midnight to midnight