Entry 2 senses · 2 variants Webster, 1913 Cobelligerent · Co·bel·lig·er·ent · IPA a. n. 01 a. Carrying on war in conjunction with another power. 1. Carrying on war in conjunction with another power. 02 n. A nation or state that carries on war in connection with another. 1. A nation or state that carries on war in connection with another.