The Collaborative International Dictionary of English v.0.48:
Alcazar \Al*ca"zar\, n. [ fr. Ar. al the + qacr (in pl.) a castle.] A fortress; also, a royal palace. --Prescott. [1913 Webster]WordNet (r) 3.0 (2006):
alcazar n 1: any of various Spanish fortresses or palaces built by the Moors