2、calendar:  English acquired calendar via Anglo-Norman calender and Old French calendier from Latin calendārium, which was a ‘moneylender’s account book’. It got its name from the calends (Latin calendae), the first day of the Roman month, when debts fell due. Latin calendae in turn came from a base *kal- ‘call, proclaim’, the underlying notion being that in ancient Rome the order of days was publicly announced at the beginning of the month.The calendula , a plant of the daisy family, gets its name from Latin calendae, perhaps owing to its once having been used for curing menstrual disorders. Calender ‘press cloth or paper between rollers’ , however, has no connection with calendar; it probably comes from Greek kúlindros ‘roller’, source of English cylinder.
4、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."