• (a.) Of or belonging to the duumviri or the duumvirate.
Du·um'vi·ral adjective [ Latin duumviralis .] Of or belonging to the duumviri or the duumvirate. 
duumvir, duumviracy, duumviral, duumvirate 1. In Roman history, one of the duumviri, the general name given to pairs of co-equal magistrates and functionaries in Rome and in her coloniae and municipia. 2. In modern use, one of two colleagues in authority.