belligerency bel·li·ge·rency uncommon noun 1. hostile or warlike attitude or nature Synonymsbelligerence 2. acts of overt warfare “the outbreak of hostilities” Synonymshostility Related words Broader terms combathostility Narrower terms warpath WordNet 2.1 (Princeton University). Wiktionary (CC BY-SA). WordNet 2.1 Copyright Princeton University. All rights reserved.