Bermuda

Atlantic island, named for Spanish explorer Juan de Bermudez(d.1570), who discovered it c. 1515.

Bermuda shorts is attested by 1946 (in "The Princeton Alumni Weekly"), from the type of garb worn by U.S. tourists there. Bermuda triangle in the supernatural sense was popular from 1972. As the adjective, Bermudian (1777) holds seniority over Bermudan (1895).