Pronunciation: (ji-brôl'tur),[key] —n. 1. a British crown colony comprising a fortress and seaport located on a narrow promontory near the S tip of Spain. 29,934; 17/8 sq. mi. (5 sq. km).
2. Rock of. a. Ancient, Calpe. a long, precipitous mountain nearly coextensive with this colony: one of the Pillars of Hercules. 1396 ft. (426 m) high; 2½ mi. (4 km) long.
b. any person or thing that has strength and endurance that can be relied on.
3. Strait of, a strait between Europe and Africa at the Atlantic entrance to the Mediterranean. 8½–23 mi. (14–37 km) wide.
4. any impregnable fortress or stronghold. —n.