Arbitrator, arbiter, arbitration and arbitrage
Do not confuse arbitrator with the very similar word arbiter. An arbitrator is someone who hears evidence and renders a decision in arbitrations but not in any other type of dispute.
If you have a mandatory arbitration clause in your contract you might not be fighting in court. Instead, you may find your case brought before an arbitrator who works for a private arbitration group.
In contrast, an arbiter is an impartial person or institution given the power to decide in any sort of controversy.
The Supreme Court is likely to be the final arbiter in this long, drawn-out and highly divisive dispute.
(However, the exception is in Scotland, where arbiters conduct arbitration.)
There are two more words which complicate the situation further—arbitration and arbitrage. Arbitration is the reference of a dispute to an impartial (third) person chosen by the parties who agree in advance to abide by the arbitration award issued after the hearing at which both parties have an opportunity to be heard.
The parties decided to refer the dispute to arbitration pursuant to the terms of their agreement.
Arbitrage is completely different; it is the simultaneous buying and selling of currencies or securities at two different prices in two different markets to profit from price discrepancies.
Index arbitrage and outright manipulation have come to dominate trading in some areas.