Vendemiaire Syllabification: (Ven·de·mi·aire)Pronunciation: /ˌvändəˈmyer, ˌväNdā-/ (also Vendémiaire)Definition of Vendemiaire noun the first month of the French Republican calendar (1793–1805), originally running from September 22 to October 21. Origin:French, from Latin vindemia 'vintage'Vendemiaire in other Oxford dictionaries Definition of Vendemiaire in the British & World English dictionary