A calendar is a seestem o organisin days for social, releegious, commercial or admeenistrative purposes. This is duin bi giein names tae periods o time, teepically days, weeks, months, an years. A date is the designation o a single, specific day within such a seestem. A calendar is an aa a pheesical record (eften paper) o such a seestem. A calendar can an aa mean a leet o planned events, such as a coort calendar or a pairtly or fully chronological leet o documents, such as a calendar o wills.
Periods in a calendar (such as years an months) are usually, tho nae necessarily, synchronised wi the cycle o the sun or the muin. The maist common teep o pre-modren calendar wis the lunisolar calendar, a lunar calendar that occasionally adds ane intercalary month tae remeen synchronised wi the solar year ower the lang term.
The calendar in maist widespread uise today is the Gregorian calendar, introduced in the 16t century bi Pape Gregory XIII as a modification o the Julian calendar, which wis itsel a modification o the auncient Roman calendar. The term calendar itsel is taken frae calendae, the term for the first day o the month in the Roman calendar, relatit tae the verb calare "tae cry oot", referrin tae the "cryin" o the new muin when it wis first seen. Laitin calendarium meant "accoont beuk, register" (as accoonts war settled an debts war collected on the calends o each month). The Laitin term wis adoptit in Auld French as calendier.
- New Shorter Oxford English Dictionary