noun
A political system where the oldest members hold the most power; often used in discussions of traditional or historical governance.
その部族は長老政治によって統治されていた。
The tribe was governed by a gerontocracy.
Compound of 長老 (elder) and 政治 (politics, government). The exact historical derivation is uncertain, but the term is a straightforward calque of the English 'gerontocracy'.