Arbiter
Arbiter ({not transcribed}) , noun
[Latin arbiter; ar- (for ad) + the root of betere to go; hence properly, one who comes up to look on.]
1.
A person appointed, or chosen, by parties to determine a controversy between them.
In modern usage, arbitrator is the technical word.
2.
Any person who has the power of judging and determining, or ordaining, without control; one whose power of deciding and governing is not limited.
For Jove is arbiter of both to man.
Arbiter , transitive verb
To act as arbiter between. [Obsolete]