Encyclopædia Britannica, Ninth Edition/December
DECEMBER, the last month of the year. In the Roman calendar, traditionally ascribed to Romulus, the year was divided into ten months, the last of which was called December, or the tenth month, and this name, though etymologically incorrect, was retained for the last or twelfth month of the year as now divided. In the Romulian calendar December had thirty days; Numa reduced the number to twenty-nine; Julius Cæsar added two days to this, giving the month its present length. The Saturnalia occurred in December, which is therefore styled “acceptus geniis” by Ovid (Fasti, iii. 58); and this also explains the phrase of Horace “libertate Decembri utere” (Sat. ii. 7). Martial applies to the month the epithet canus (hoary), and Ovid styles it gelidus (frosty) and fumosus (smoky). The Saxons called it winter-monat, or winter month, and heligh-monat, or holy month, from the fact that Christmas fell within it. The 22d December is the date of the winter solstice, when the sun reaches the tropic of Capricorn.