Relating to or characteristic of a duumvir or duumvirate; of or pertaining to joint rule by two people.
From duumvir + -al (adjective suffix). Duumvir is from Latin 'duo' (two) + 'vir' (man), with -al being a standard adjectival suffix from Latin.
This word is almost exclusively found in ancient Roman history texts, but it reminds us that the very idea of 'checks and balances' through shared power is ancient!
Complete word intelligence in one call. Free tier — 50 lookups/day.