arbiter
/ˈɑːbɪtə(r)/noun
1- a person who settles a dispute or has ultimate authority in a matter仲裁人, 公断人：
the military acted as arbiter of conflicts between political groups.
军方担任了不同政治团体之间纷争的仲裁人。
1.1
- a person whose views or actions have great influence over trends in social behaviour（社会行为的）评判人, 引领者：
an arbiter of taste.
品味的引领者。
词源
late Middle English: from Latin， 'judge， supreme ruler'.