Brumaire, the name of the second month in the French Revolutionary Calendar which was established in France by a decree of the National Convention on 5 October in the year II, completed with regard to nomenclature by Fabre d’Eglantine, and promulgated in its new form on 4 Frimaire in the year II (24 November 1793). The month of Brumaire began on the day which corresponded, according to the year, to October 22 or to October 23 of the old calendar, and ended on November 20 or November 21. It was divided into decades like the other months of the republican calendar. Its name alludes to the fogs and mists (brumes in French) which occur frequently at that time of the year.
In political/historical usage, Brumaire often refers to the coup d'état of 18 Brumaire in the year VIII (9 November 1799), by which General Napoleon Bonaparte overthrew the government of the Directory to replace it by the Consulate.