Gibraltar, Rock of Gibraltar, Calpe - location of a colony of the United Kingdom on a limestone promontory at the southern tip of Spain; strategically important because it can control the entrance of ships into the Mediterranean; one of the Pillars of Hercules --1is a kind ofcolony, settlement; promontory, headland, foreland --1is a part of Pillars of Hercules; Europe --1has members: Gibraltarian