ordnance Syllabification: (ord·nance)Pronunciation: /ˈôrdnəns/Translate ordnance | into Italian Definition of ordnance noun 1mounted guns; artillery. military weapons, ammunition, and equipment used in connection with them. 2a branch of the armed forces dealing with the supply and storage of weapons, ammunition, and related equipment. Origin: late Middle English: variant of ordinanceordnance in other Oxford dictionaries Definition of ordnance in the British & World English dictionary