noun
diarchy; dyarchy
A political system in which two individuals jointly rule, often used in historical or political science contexts.
古代スパルタでは両頭政治が行われていた。
Ancient Sparta practiced a diarchy.
Synonym; 二頭政治 is also used for diarchy, but 両頭政治 is less common.
Compound of 両頭 (both heads) and 政治 (politics). The exact historical derivation is uncertain; the term is a modern coinage for the concept of dual rule.