1. Roman law. Magistrates elected or appointed in pairs to hold an office or perform a function.
duumviri municipales (d[y]oo-[schwa]m-v[schwa]-rI myoo-nis-[schwa]-pay-leez). [Latin] Two judicial magistrates annually elected in towns and colonies.
duumviri navales (d[y]oo-[schwa]m-v[schwa]-rI n[schwa]-vay-leez). [Latin] Two officers appointed to man, equip, and refit the navy.
2. Two peers in authority.
— Also termed duoviri.