That would be Taiwan.
formosa
Taiwan (formally Formosa)
It is formally known as the Republic of China. Taiwan was named Formosa ("beautiful [island]") by Portuguese explorers, so Westerners did know the island as "Formosa" until the 20th century. On mainland China, Taiwan is written 台湾, and spelled Táiwan in pinyin. On Taiwan, the name is written 臺灣, and spelled Taiwan or T'ai-wan in roman letters. The difference in Chinese characters has to do with the fact that on mainland China they now use "simplified characters" that the Taiwanese do not use. When the Dutch were running a colonial trade company based on Taiwan, they also used the spelling Tayoan, which is pronounced the same as "Taiwan."
Taiwan was formerly known as Formosa
The Republic of China is better known as Taiwan.
In most cases, you probably want formerly known as, referring to an old name that is no longer used. For example, "Benin, formerly known as Dahomey, is a country in West Africa."In the alternative, formally known as refers to a fancy name that is usually abbreviated in ordinary use. For example, "The UK, formally known as the United Kingdom of Great Britain and Northern Ireland, is a country in Europe."
The Nationalist Chinese retreated to the island of Taiwan.
Taiwan is also known as the Republic of China (ROC). This name originates from the government that retreated to the island after the Chinese Civil War in 1949. While it is commonly referred to as Taiwan, the ROC title reflects its historical context and political status.
The main island of Taiwan, also known as Formosa (from Portuguese (Ilha) Formosa, meaning "beautiful (island)") (Wikipedia) so Taiwan also called Formosa
Taiwan is the new name of FORMOSA.. :]
Coin collecting is formally known as "numismatics" and people who participate in numismatics are known as numismatists.