December (Roman month) "(VII Kal. Ian." on the pre-Julian calendar, when December had only 29 days). On the calendar of the Roman Republic and early Principate, each day was marked with a letter to denote its religiously lawful status. By the late 2nd century AD, extant calendars no longer show days marked with these letters, probably in part as a result of calendar reforms undertaken by Marcus Aurelius. Days were also marked with nundinal letters in cycles of "A B C D E F G H", to mark the "market week" December (Roman month) December (from Latin "decem", "ten") or mensis December was
December (Roman month) fixed points of the month: the Nones (5th or 7th), the Ides (13th or 15th), and the Kalends (1st) of the following month. The Nones of December was the 5th, and the Ides the 13th. The last day of December was the "pridie Kalendas Ianuarias," "day before the Januarian Kalends". Roman counting was inclusive; December 9 was "ante diem V Idūs Decembrīs", "the 5th day before the Ides of December," usually abbreviated "a.d. V Id. Dec." (or with the "a.d." omitted altogether); December 24 was "IX Kal. Ian.", "the 9th day before the Kalends of Ianuarius," on the Julian calendar