noun
A political system where the elderly hold power. A formal, academic term.
その国は事実上のジェロントクラシーだと言われている。
That country is said to be a de facto gerontocracy.
A more native Japanese term for rule by elders, but less common than the loanword ジェロントクラシー in academic contexts.
From English 'gerontocracy', ultimately from Greek 'geron' (old man) and 'kratos' (power).