What's the difference between duumvir and duumviri?
Duumvir
Definition:
(n.) One of two Roman officers or magistrates united in the same public functions.
Example Sentences:
(1) The pugnacious Luzhkov, who ran Moscow from 1992, was dismissed after apparently growing too powerful and falling out with Russia's ruling Putin-Medvedev duumvirate.
(2) Some believe the attacks on Luzhkov reflect increasing tensions within Russia's ruling Putin-Medvedev duumvirate, ahead of presidential elections in 2012.