a person older than oneself; a senior or elder (someone of greater age or experience).
公共の場では年長者に席を譲るのが礼儀だ。
It's polite to give up your seat to an elder in public places.
クラスで一番の年長者がまとめ役になった。
The oldest student in the class became the coordinator.
年長者の意見を尊重する文化がある地域も多い。
There are many regions where there's a culture of respecting elders' opinions.