calendar

noun

1. a table or register with the days of each month and week in a year: He marked the date on his calendar.
2. any of various systems of reckoning time, especially with reference to the beginning, length, and divisions of the year.Compare Chinese calendar, Gregorian calendar, Hindu calendar, Jewish calendar, Julian calendar, Muslim calendar.
3. a list or register, especially one arranged chronologically, as of appointments, work to be done, or cases to be tried in a court.
4. a list, in the order to be considered, of bills, resolutions, etc., brought before a legislative body.
5. Obsolete. a guide or example.

verb (used with object)

6. to enter in a calendar; register.

noun

1. a system for determining the beginning, length, and order of years and their divisionsSee also Gregorian calendar, Jewish calendar, Julian calendar, Revolutionary calendar, Roman calendar
2. a table showing any such arrangement, esp as applied to one or more successive years
3. a list, register, or schedule of social events, pending court cases, appointments, etc

verb

4. (tr) to enter in a calendar; schedule; register

n.

c.1200, “system of division of the year;” mid-14c. as “table showing divisions of the year;” from Old French calendier “list, register,” from Latin calendarium “account book,” from calendae/kalendae “calends” the first day of the Roman month — when debts fell due and accounts were reckoned — from calare “to announce solemnly, call out,” as the priests did in proclaiming the new moon that marked the calends, from PIE root kele- (2) “to call, shout” (see claim (v.)).

Taken by the early Church for its register list of saints and their feast days. The -ar spelling in English is 17c. to differentiate it from the now obscure calender “cloth-presser.”