cal•en•darˈkæl ən dər(n.)

1. a table or register with the days of each month and week in a year.

   Category: Horology

2. any of various systems of reckoning time, esp. with reference to the beginning, length, and divisions of the year, as the Gregorian calendar or the Julian calendar.

   Category: Horology

3. a list or register, esp. one arranged chronologically, as of appointments, cases to be tried in court, or bills to be considered by a legislature.

   Category: Government

4. Obs. a guide or example.

5. (v.t.)to enter in a calendar; register.

Origin of calendar:

1175–1225; ME calender < AF < L calendārium account book, der. of Calend(ae)calends (when debts were due)

ca•len•dri•calkəˈlɛn drɪ kəl(adj.)