calendar

US /ˈkæl.ən.dɚ/
UK /ˈkæl.ən.dɚ/
"calendar" picture
1.

a chart or series of pages showing the days, weeks, and months of a particular year, or giving particular seasonal information

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I marked the appointment on my calendar.
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The new year's calendar has beautiful landscapes.
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almanacdiaryplanner
2.

a system by which the beginning, length, and divisions of the year are fixed

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The Gregorian calendar is widely used around the world.
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Ancient civilizations developed their own unique calendars.