A small rocky and barren island, one of the group called the “Sporades,” in the Aegean Sea. It is mentioned in Scripture only in Rev_1:9. It was on this island, to which John was banished by the emperor Domitian (A.D. 95), that he received from God the wondrous revelation recorded in his book. This has naturally invested it with the deepest interest for all time. It is now called Patmo.
Easton’s Bible Dictionary