calendar Definition

a system for fixing the beginning, length, and divisions of the civil year and arranging days and longer divisions of time (such as weeks and months) in a definite order

a tabular register of days according to a system usually covering one year and referring the days of each month to the days of the week

an orderly list: such as

to enter in a calendar

a period of a year beginning and ending with the dates that are conventionally accepted as marking the beginning and end of a numbered year

a period of time equal in length to that of the year in the calendar conventionally in use

a calendar in general use introduced in 1582 by Pope Gregory XIII as a revision of the Julian calendar, adopted in Great Britain and the American colonies in 1752, marked by the suppression of 10 days or after 1700 11 days, and having leap years in every year divisible by four with the restriction that centesimal years are leap years only when divisible by 400

a lunar calendar usually dating from 3101 b.c. and used especially in India

a lunar calendar reckoned from the Hegira in a.d. 622 and organized in cycles of 30 years

a calendar in use among Jewish peoples that is reckoned from the year 3761 b.c. and dates in its present form from about a.d. 360

a calendar introduced in Rome in 46 b.c. establishing the 12-month year of 365 days with each fourth year having 366 days and the months each having 31 or 30 days except for February which has 28 or in leap years 29 days

islamic calendar

a table for finding the day of the week for any one of a wide range of dates