The country's official name was Siam (Thai: สยาม RTGS: Sayam, IPA: [sàjǎːm]) until June 23, 1939, when it was changed to Thailand. It was then renamed Siam from 1945 to May 11, 1949, after which it was again renamed Thailand. Also spelled Sayam, Syâm or Syâma, it has been identified with the Sanskrit Śyâma (श्याम, meaning "dark" or "brown"). The names Shan and A-hom seem to be variants of the same word, and Śyâma is possibly not its origin but a learned and artificial distortion.
The word Thai (ไทย) is not, as commonly believed, derived from the word Tai (ไท) meaning "freedom" in the Thai language; it is, however, the name of an ethnic group from the central plains (the Thai people). A famous Thai scholar argued that Tai (ไท) simply means "people" or "human being" since his investigation shows that in some rural areas the word "Tai" was used instead of the usual Thai word "khon" (คน) for people. The Thai use the phrase "land of the free" to express pride in the fact that Thailand is the only country in Southeast Asia never colonized by an outside power.
While the Thai people will often refer to their country using the polite form Prathet Thai (Thai: ประเทศไทย), they most commonly use the more colloquial word Mueang Thai (Thai: เมืองไทย) or simply Thai (Thai: ไทย); the word mueang (Thai: เมือง) meaning nation but most commonly used to refer to a city or town. Ratcha Anachak Thai (Thai: ราชอาณาจักรไทย) means "Kingdom of Thailand".
Etymologically, its components are: -Ratcha- (from Sanskrit raja, meaning "king, royal, realm") ; -ana- (from Pāli āṇā, "authority, command, power", itself from Sanskrit ājñā, same meaning) -chak (from Sanskrit cakra or cakraṃ meaning "wheel", a symbol of power and rule). The Thai National Anthem (Thai: เพลงชาติ) refers to the Thai nation as: prathet-thai (Thai: ประเทศไทย). The first line of the national anthem is: prathet thai ruam lueat nuea chat chuea thai (Thai: ประเทศไทยรวมเลือดเนื้อชาติเชื้อไทย) and was translated in 1939 by Colonel Luang Saranuprabhandi as: “Thailand is the unity of Thai blood and body.”
word of god