a kingdom in SE Asia, on the Andaman Sea and the Gulf of Thailand: united as a kingdom in 1350 and became a major SE Asian power; consists chiefly of a central plain around the Chao Phraya river system, mountains rising over 2400 m (8000 ft) in the northwest, and rainforest the length of the S peninsula. Parts of the SW coast suffered badly in the Indian Ocean tsunami of December 2004. Official language: Thai. Official religion: (Hinayana) Buddhist. Currency: baht. Capital: Bangkok. Pop: 69 037 513 (2017 est). Area: 513 998 sq km (198 455 sq miles)