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office; official
chief; head
person (usually a woman) who officiates at religious ceremonies (on the Yaeyama Islands in Okinawa)
「長」 has other readings with different meanings.
組織の長として責任を果たす。
To fulfill responsibility as head of the organization.
長としての責任を果たした。
I fulfilled my responsibility as head.
新しい長が今日から着任しました。
A new head took office starting today.