Seoul, the capital of South Korea, has been called by a number of formal and informal names over time. The word seoul was originally a common noun that simply meant "capital city", and was used colloquially to refer to the capital throughout Korean history. Seoul became the official name of the South Korean capital after its liberation from Japan after the Second World War.
Historically, the city of what is now Seoul has been called in various names, including Wiryeseong, Bukhansangun, Hanyang, Namgyeong, Hanyangbu, and Hanseong.