Various names for the island of Taiwan remain in use today, each derived from explorers or rulers during a particular historical period. The name Formosa (福爾摩沙) dates from 1542, when Portuguese sailors sighted an uncharted island and noted it on their maps as Ilha Formosa ("beautiful island"). The name "Formosa" eventually "replaced all others in European literature" and remained in common use among English speakers into the 20th century.
In the early 17th century, the Dutch East India Company established a commercial post at Fort Zeelandia (modern-day Anping, Tainan) on a coastal sandbar called "Tayouan", after their ethnonym for a nearby Taiwanese aboriginal tribe, possibly Taivoan people, written by the Dutch and Portuguese variously as Taiouwang, Tayowan, Teijoan, etc. This name was also adopted into the Chinese vernacular (in particular, Hokkien, as Pe̍h-ōe-jī: Tāi-oân/Tâi-oân) as the name of the sandbar and nearby area (Tainan). The modern word "Taiwan" is derived from this usage, which is seen in various forms (大員, 大圓, 大灣, 臺員, 臺圓 and 臺窩灣) in Chinese historical records. The area occupied by modern-day Tainan represented the first permanent settlement by both European colonists and Chinese immigrants. The settlement grew to be the island's most important trading centre and served as its capital until 1887. Use of the current Chinese name (臺灣) was formalized as early as 1684 with the establishment of Taiwan Prefecture. Through its rapid development the entire Formosan mainland eventually became known as "Taiwan".
In his Daoyi Zhilüe (1349), Wang Dayuan used "Liuqiu" as a name for the island of Taiwan, or the part of it closest to Penghu.
Elsewhere, the name was used for the Ryukyu Islands in general or Okinawa, the largest of them; indeed the name Ryūkyū is the Japanese form of Liúqiú.
The name also appears in the Book of Sui (636) and other early works, but scholars cannot agree on whether these references are to the Ryukyus, Taiwan or even Luzon.
The official name of the state is the "Republic of China"; it has also been known under various names throughout its existence. Shortly after the ROC's establishment in 1912, while it was still located on the Chinese mainland, the government used the short form "China" (Zhōngguó (中國)) to refer to itself, which derives from zhōng ("central" or "middle") and guó ("state, nation-state"),[d] a term which also developed under the Zhou dynasty in reference to its royal demesne,[e] and the name was then applied to the area around Luoyi (present-day Luoyang) during the Eastern Zhou and then to China's Central Plain before being used as an occasional synonym for the state during the Qing era. During the 1950s and 1960s, after the government had withdrawn to Taiwan upon losing the Chinese Civil War, it was commonly referred to as "Nationalist China" (or "Free China") to differentiate it from "Communist China" (or "Red China"). It was a member of the United Nations representing "China" until 1971, when it lost its seat to the People's Republic of China. Over subsequent decades, the Republic of China has become commonly known as "Taiwan", after the island that comprises 99% of the territory under its control. In some contexts, especially ROC government publications, the name is written as "Republic of China (Taiwan)", "Republic of China/Taiwan", or sometimes "Taiwan (ROC)." The Republic of China participates in most international forums and organizations under the name "Chinese Taipei" due to diplomatic pressure from the People's Republic of China. For instance, it is the name under which it has competed at the Olympic Games since 1984, and its name as an observer at the World Health Organization.