- a country fighting in a war on the side of another country
WordReference Random House Unabridged Dictionary of American English © 2026
co•bel•lig•er•ent
(kō′bə lij′ər ənt),USA pronunciation n.
- a state or individual that cooperates with, but is not bound by a formal alliance to another in waging war.
- co- + belligerent 1805–15
Collins Concise English Dictionary © HarperCollins Publishers::
cobelligerent /ˌkəʊbɪˈlɪdʒərənt/ n