Definition

1. Noun:
   • A calendar month is one of the twelve named periods into which a year is divided in a calendar system, such as the Gregorian calendar. It is a unit of time approximately based on the natural period of the Moon's phases, though most modern calendars have months of fixed lengths (28, 30, or 31 days) that only roughly correspond.

Usage

• A calendar month is used to specify a particular period within a year for scheduling, planning, or describing when an event occurs. It is distinct from a lunar month or an arbitrary four-week period.
• Example: "The project must be completed within a calendar month." (This means it must be finished by the same date in the following month, not necessarily in exactly 30 days.)

Examples

• Noun:
  • January is the first calendar month of the year.
  • He paid the bill last month. (Here, "month" implicitly means the previous calendar month.)
  • The rent is due on the first day of each calendar month.

Advanced Usage

• "A calendar month's notice": A formal notice period that expires on the same date in the following month.
  • You must give a calendar month's notice before terminating the contract.
• Distinction from "lunar month": A calendar month is an administrative division, while a lunar month (~29.5 days) is based on the moon's cycle.
  • The Islamic calendar is based on lunar months, not fixed calendar months.

Variants and Related Words

• Month (n): The more common, general term for which "calendar month" is a specific type.
• Lunar month (n): A month measured by the cycle of the moon's phases.
• Billing month (n): A specific period used by a company for invoicing, which may or may not align exactly with a calendar month.

Synonyms

• Month: The most direct synonym, though it can be ambiguous without context.
• Thirty-day period: An approximate synonym, though not all calendar months have 30 days.

Related Phrases

• Per calendar month: Used to indicate a rate or frequency.
  • The subscription costs ten dollars per calendar month.
• Month-end: The conclusion of a calendar month.
  • The financial report is prepared for month-end.

Notes

• The concept of a calendar month is fundamental to organizing civil life, including finance, law, and planning. It is a standardized period, whereas other uses of "month" (e.g., "a month ago") can be more fluid, referring to roughly four weeks prior.

Noun

1. one of the twelve divisions of the calendar year
   • he paid the bill last month