Romanization of Thai

There are many systems for the romanization of the Thai language, i.e. representing the language in Latin script. These include systems of transliteration, and transcription.

An international standard, ISO 11940, was devised with transliteration in academic context as one of its main goals.

An extension to it, ISO 11940-2, describes conversion of it to a simplified transcription, which is almost identical to the Royal Thai General System of Transcription (RTGS)—the official scheme promulgated by the Royal Thai Institute. These are not reversible, as they do not indicate tone and underrepresent vowel quality and quantity. Graphemic distinctions between letters for Indic voiced, voiceless, and breathy-voiced consonants have also been neutralised.

In practice, often non-standard and inconsistent romanizations are used, especially for proper nouns and personal names. This is reflected, for example, in the name Suvarnabhumi Airport, which is spelled based on direct transliteration of the name's Sanskrit root.

Libraries in English-speaking countries use the ALA-LC Romanization.

Some scholars use the transliteration system by Georges Cœdès, in the version published by his student Uraisi Varasarin.

The ISO standard ISO 11940 is based on Thai orthography, and defines a reversible transliteration by means of adding a host of diacritics to the Latin letters. The result bears little resemblance to the pronunciation of the words.

The Cœdès system for Thai transliteration also constitutes a reversible transliteration. In this system, the same transliteration is proposed for Thai and Khmer whenever possible.

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