1. a chart or series of pages showing the days, weeks, and months of a particular year
2. a system for organizing days into weeks, months, and years
3. a schedule of planned events or activities

1. to schedule or enter in a calendar

Examples

• She marked her birthday on the wall calendar.
• The Gregorian calendar is used in most countries today.
• Check your calendar to see if you’re free next Tuesday.
• The school calendar shows when classes begin and end.
• Please calendar our meeting for next week.
• His social calendar is completely booked this month.
• The ancient Romans used a different calendar system.