Kalendar
The Cyclopedic Law Dictionary · Walter A. Shumaker and George Foster Longsdorf; ed. James C. Cahill · 1922
The Cyclopedic Law Dictionary
The original form of "calendar." KALENDARIUM (Lat.) In civil law. A calendar; a book of accounts, memorandum book, or debt books; a book in which accounts were kept of moneys loaned out on interest.
Dig. 32. 64.
So called because ^le Romans used to let out their money, and receive the interest on the calends of each month. Calv. Lex.