Calendar: The Latin 'kalendārium' was… | etymologist.ai
calendar
/ˈkæl.ən.dəɹ/·noun·13th century·Established
Origin
From Latin 'kalendarium' (account book), from 'kalendae' (first of the month, when debts were due) — originally a debt register.
Definition
A system of organizing days for social, religious, commercial, or administrative purposes; a chart or series of pagesshowing such a system.
The Full Story
Latin13th centurywell-attested
From Latin calendārium (account book, register of debts), from calendae (the Kalends — the first day of each Roman month, when debts were due and interest was paid). The Kalends is likely from Latin calāre (to call out, proclaim), because the new month was publicly proclaimed by a priest who observed the new moon. Calāre derives from the PIE root *kelh₁- (to shout, call), which also yielded Greek kalein (to call — hence English
Did you know?
The Latin 'kalendārium' was originally an account book, not a date chart — it tracked when debts were due on the calends (first of each month). The shift from 'debt ledger' to 'date system' happened because time-keeping and money-tracking were functionally the same thing in Roman commercial life.
— hence English clear, clarify, declare), Latin classis (a summoning, a class — hence English class), and Old English hlōwan (to low, bellow). The semantic