a sultanate in SE Arabia, on the Gulf of Oman and the Arabian Sea: the most powerful state in Arabia in the 19th century, ruling Zanzibar, much of the Persian coast, and part of Pakistan. Official language: Arabic. Official religion: Muslim. Currency: rial. Capital: Muscat. Pop: 4 636 262 (2017 est). Area: about 306 000 sq km (118 150 sq miles)