From Old Spanish carcax, from Old French carcois, carquais, tarquait, tarchais, borrowed in turn from Byzantine Greek καρκάσιον (karkásion), a medieval variant of ταρκάσιον (tarkásion), from Arabic تِرْكَاش (tirkāš), from Persian تیرکش (tirkaš). The -x in Old Spanish may be due to Old Catalan carcax (modern Catalan carcaix) as an intermediate.