calendar-n; 2 Senses

Sense Number 1: A system of timekeeping that defines the beginning, length, and divisions of the year.

Commentary: CALENDAR[+abstract]

The Mayan calendar is still one of the most advanced systems.
The Gregorian calendar defines a certain number of months.

WordNet 3.0 Sense Numbers: 1

Sense Number 2: A physical representation of a timekeeping system.

Commentary: CALENDAR[+concrete]

I have you on my calendar for next Monday.
The calendar hung on the wall in his office.
I have a computer program to make calendars for printing.

WordNet 3.0 Sense Numbers: 2, 3