The way it is raised the question lends itself to two interpretations: ) The etymology of the word and b ) explain what is such language. Siam was a Kingdom located in Southeast Asia and realized the space today occupied Thailand, Cambodia and Laos. In 1932 Siam changed its name to Thailand, which is as we know it now. The primary language of Thailand is the Siamese or Thai, but not the only one. Now, if Adolfo what he wants is the etymological approach, many lights of the subject could be found in http://es.wikipedia.org/wiki/Idioma_tailand is and would complement its investigation calling the diplomatic Agency of Thailand that surely exists in his country to make the specific question there. If you decide, good luck in that management, Adolfo.Aunque would be leaving by roads of ultra petita, it is worth to remember the origin of the word Siamese. This voice is applied to a person who has been born joined his twin brother on the one hand of the body. The case of the brothers Chang and Eng Bunker, the world famous conjoined twins from Siam, that surgery could not separate because they were United by the chest, were the reference for the current use of Siamese. They were presented as attraction at the circus Barnum 38; Baily and settled in the USA. When one of them paid tribute to nature the other followed after a short space of time.