twelfth lunar month; 12th month of the lunar calendar
Refers to the last month of the traditional lunar calendar, roughly corresponding to December–January. In modern Japanese, 師走 (しわす) is the common word for December in the old calendar; 臘月 is a rare, literary, or historical term.
See also: 師走
The twelfth lunar month corresponds to the period from December to January in the modern calendar.
The term 臘月 appears in this old document.