The Thai script (, , ) is the abugida used to write Thai, Southern Thai and many other languages spoken in Thailand. The Thai script itself (as used to write Thai) has 44 consonant symbols (, ), 16 vowel symbols (, ) that combine into at least 32 vowel forms, four tone diacritics ( or , or ), and other diacritics.
Although commonly referred to as the Thai alphabet, the script is not a true alphabet but an abugida, a writing system in which the full characters represent consonants with diacritical marks for vowels; the absence of a vowel diacritic gives an implied 'a' or 'o'. Consonants are written horizontally from left to right, and vowels following a consonant in speech are written above, below, to the left or to the right of it, or a combination of those.
History
The Thai script is derived from the Old Khmer script (, akson khom), a sophisticated writing system rooted in the South Indian Pallava alphabet () and a southern branch of the ancient Brahmi tradition. The Sukhothai script was the earliest Thai script developed from the Old Khmer script. The Ram Khamhaeng Inscription dated to 1292 is often cited as the script's first appearance, yet many scholars question its authenticity and reliability as historical evidence. However, according to the Wat Bang Sanuk Inscription (C.107) in Phrae province, several scholars proposed that the earliest Thai script could be dated back to 1219.
The introduction of tone markers in the Thai script was an adaptation to record tonal features absent in the source languages such as Dravidian languages, Indo-Aryan languages and the Mon-Khmer (Austroasiatic languages) family. Although Chinese and other Sino-Tibetan languages have distinctive tones in their phonological system, no tone marker is found in their orthographies. Another addition was consonant clusters that were written horizontally and contiguously, rather than writing the second consonant below the first one. The vowel marks were written on the main line. However, the practices fell out of use not long after.
Orthography
There is a fairly complex relationship between spelling and sound. There are various issues: For many consonant sounds, there are two different letters that both represent the same sound, but which cause a different tone to be associated. This stems from a major change (a tone split) that occurred historically in the phonology of the Thai language. At the time the Thai script was created, the language had three tones and a full set of contrasts between voiced and unvoiced consonants at the beginning of a syllable (e.g. z vs. s). At a later time, the voicing distinction disappeared, but in the process, each of the three original tones split in two, with an originally voiced consonant (the modern "low" consonant signs) producing a lower-variant tone, and an originally unvoiced consonant (the modern "mid" and "high" consonant signs) producing a higher-variant tone. Thai borrowed a large number of words from Sanskrit and Pali, and the Thai alphabet was created so that the original spelling of these words could be preserved as much as possible. This means that the Thai alphabet has a number of "duplicate" letters that represent separate sounds in Sanskrit and Pali (e.g. the alveolo-palatal fricative ś) but which never represented distinct sounds in the Thai language. Some are used to indicate tone distinctions as mentioned above, and others are mostly or exclusively used in Sanskrit and Pali borrowings. The desire to preserve original Sanskrit and Pali spellings also produces a particularly large number of duplicate ways of spelling sounds at the end of a syllable (where Thai is strictly limited in the sounds that can occur but Sanskrit allowed all possibilities, especially once former final /a/ was deleted), as well as a number of silent letters. Moreover, many consonants from Sanskrit and Pali loanwords are generally silent. The spelling of the words resembles Sanskrit or Pali orthography: Thai (spelled sǎamaarth but pronounced sa-mat with a silent r and a plain t that is represented using an aspirated consonant) "to be able" (Sanskrit समर्थ samartha) Thai (spelled chanthr but pronounced chan because the th and the r are silent) "moon" (Sanskrit चन्द्र chandra) Thai phonology dictates that all syllables must end in a vowel, an approximant, a nasal, or a voiceless plosive. Therefore, the letter written may not have the same pronunciation in the initial position as it does in the final position. Even though the high class letter ho hip is used to write the sound /h/, if the letter comes before a low class letter in a syllable, it becomes the silent ho nam and turn the initial consonant into high class.
Thai letters do not have upper- and lower-case forms like Latin letters do. Spaces between words are not used, except in certain linguistically motivated cases.
Punctuation Minor pauses in sentences may be marked by a comma ( or , or ), and major pauses by a period ( or , or ), but most often are marked by a blank space (, ). Thai writing also uses quotation marks (, ) and parentheses (round brackets) (, or , ), but not square brackets or braces.
A () is used for abbreviation. A () is the same as "etc." in English.
Several obsolete characters indicated the beginning or ending of sections. A bird's eye (, , officially called , ) formerly indicated paragraphs. An () was formerly used to mark the end of a chapter. A () was formerly used to mark the end of a document, but is now obsolete.
Alphabet listing
Thai (along with its sister system, Lao) lacks conjunct consonants and independent vowels, while both designs are common among Brahmic scripts (e.g., Burmese and Balinese).Unicode Consortium. "Southeast Asia". In The Unicode Standard Version 12.0 (p. 631). In scripts with conjunct consonants, each consonant has two forms: base and conjoined. Consonant clusters are represented with the two styles of consonants. The two styles may form typographical ligatures, as in Devanagari. Independent vowels are used when a syllable starts with a vowel sign.
Consonants
There are 44 consonant letters representing 21 distinct consonant sounds. Duplicate consonants either correspond to sounds that existed in Old Thai at the time the alphabet was created but no longer exist (in particular, voiced obstruents such as d), or different Sanskrit and Pali consonants pronounced identically in Thai. There are in addition four consonant-vowel combination characters not included in the tally of 44.
Consonants are divided into three classes—in alphabetical order these are middle (, ), high (, ), and low (, ) class—as shown in the table below. These class designations reflect phonetic qualities of the sounds to which the letters originally corresponded in Old Thai. In particular, "middle" sounds were voiceless unaspirated stops; "high" sounds, voiceless aspirated stops or voiceless fricatives; "low" sounds, voiced. Subsequent sound changes have obscured the phonetic nature of these classes.Modern Thai sounds /b/ and /d/ were formerly—and sometimes still are—pronounced /ʔb/ and /ʔd/. For this reason, they were treated as voiceless unaspirated, and hence placed in the "middle" class; this was also the reason they were unaffected by the changes that devoiced most originally voiced stops. Today, the class of a consonant without a tone mark, along with the short or long length of the accompanying vowel, determine the base accent (, ). Middle class consonants with a long vowel spell an additional four tones with one of four tone marks over the controlling consonant: , , , and . Only middle class consonants can take the latter two, as shown in the . Differing interpretations of the two marks or their absence allow low class consonants to spell tones not allowed for the corresponding high class consonant. In the case of digraphs where a low class follows a higher class consonant, often the higher class rules apply, but the marker, if used, goes over the low class one; accordingly, and may be considered to be digraphs as such, as explained below the Tone table.Only low class consonants may have a base accent determined by the syllable being both long and dead. Notes
To aid learning, each consonant is traditionally associated with an acrophonic Thai word that either starts with the same sound, or features it prominently. For example, the name of the letter is kho khai (), in which kho is the sound it represents, and khai () is a word which starts with the same sound and means "egg".
Two of the consonants, (kho khuat) and (kho khon), are no longer used in written Thai, but still appear on many keyboards and in character sets. When the first Thai typewriter was developed by Edwin Hunter McFarland in 1892, there was simply no space for all characters, thus two had to be left out. Also, neither of these two letters correspond to a Sanskrit or Pali letter, and each of them, being a modified form of the letter that precedes it (compare and ), has the same pronunciation and the same consonant class as the preceding letter, thus making them redundant. They used to represent the sound in Old Thai, but it has merged with in Modern Thai.
Equivalents for romanisation are shown in the table below. Many consonants are pronounced differently at the beginning and at the end of a syllable. The entries in columns initial and final indicate the pronunciation for that consonant in the corresponding positions in a syllable. Where the entry is '-', the consonant may not be used to close a syllable. Where a combination of consonants ends a written syllable, only the first is pronounced; possible closing consonant sounds are limited to 'k', 'm', 'n', 'ng', 'p' and 't'.
Although official standards for romanisation are the Royal Thai General System of Transcription (RTGS) defined by the Royal Thai Institute, and the almost identical defined by the International Organization for Standardization, many publications use different romanisation systems. In daily practice, a bewildering variety of romanisations are used, making it difficult to know how to pronounce a word, or to judge if two words (e.g. on a map and a street sign) are actually the same. For more precise information, an equivalent from the International Phonetic Alphabet (IPA) is given as well.
Alphabetic Symbol Name RTGS IPA Class Thai RTGS Meaning Initial Final Initial Final chicken k k mid egg kh k high bottle (obsolete) kh – – high water buffalo kh k low human, person (obsolete) kh – – low bell kh k low snake ng ng low plate ch t mid ching ch – high elephant ch t low chain s t low tree ch t low woman y n low makuṭa d t mid goad, javelin, spear t t mid pedestal th t high Montho th or d t or low elder th t low samanera n n low child d t mid turtle t t mid sack th t high soldier th t low flag th t low mouse, rat n n low leaf b p mid fish p p mid bee ph – high lid f – high phan ph p low tooth f p low junk ph p low horse m m low giant, yaksha y low boat, ship r n low monkey l n or /w/ low ring w low pavilion, sala s t high rishi s t high tiger, big cat s t high chest, box h – high chula kite l n low basin, tub – mid owl h – low
Notes
Phonetic The consonants can be organised by place and manner of articulation according to principles of the International Phonetic Association. Thai distinguishes among three voice/aspiration patterns for plosive consonants: unvoiced, unaspirated unvoiced, aspirated voiced, unaspirated
Where English has only a distinction between the voiced, unaspirated and the unvoiced, aspirated , Thai distinguishes a third sound which is neither voiced nor aspirated, which occurs in English only as an allophone of , approximately the sound of the p in "spin". There is similarly a laminal denti-alveolar , , triplet. In the velar series there is a , pair and in the postalveolar series the , pair.