From Middle Persian [Book Pahlavi needed] (lwstʾk' /⁠rōstāg⁠/), whence Classical Syriac ܪܘܣܬܩܐ (rustāqā), Arabic رُسْتَاق (rustāq). Akin to Old Armenian ռոտաստակ (ṙotastak) borrowed from the Parthian cognate.