Alcazar (Arab., the royal castle). I. In Spanish, the general name for a castle or citadel - applied to the castles at Seville and Segovia, and to many others.

II. Alcazar de San Juan, a town of Spain, in New Castile, in the province and 48 m. N. E. of Ciudad Real; pop. about 8,000. It has manufactures of saltpetre, soap, chocolate, etc., and is also a railway centre, where the line from Valencia joins that from Madrid to Cordova. Near it are rich iron pits.