In modern Arabic, the name is usually "Ṭaysafūn" () or "Qaṭaysfūn" () or as "al-Mada'in" ( "The Cities", referring to Greater Ctesiphon). "According to Yāqūt [...], quoting Ḥamza, the original form was Ṭūsfūn or Tūsfūn, which was arabicized as Ṭaysafūn." The Armenian name of the city was "Tizbon" (). Ctesiphon is first mentioned in the Book of Ezra of the Old Testament as Kasfia/Casphia (a derivative of the ethnic name, Cas, and a cognate of Caspian and Qazvin). It is also mentioned in the Talmud as Aktisfon. In another Talmudic reference it is written as Akistfon, located across the Tigris River from the city of Ardashir.