Thai, or Central Thai (historically Siamese; ), is a Tai language of the KraâÂÂDai language family spoken by the Central Thai, Mon, Lao Wiang, and Phuan people in Central Thailand and the vast majority of Thai Chinese enclaves throughout the country. It is the sole official language of Thailand.
Thai is the most spoken of over 60 languages of Thailand by both number of native and overall speakers. Over half of its vocabulary is derived from or borrowed from Pali, Sanskrit, Mon and Old Khmer. It is a tonal and analytic language. Thai has a complex orthography and system of relational markers. Spoken Thai, depending on standard sociolinguistic factors such as age, gender, class, spatial proximity, and the urban/rural divide, is partly mutually intelligible with Lao, Isan, and some fellow Thai topolects. These languages are written with slightly different scripts, but are linguistically similar and effectively form a dialect continuum.
The Thai language is spoken by over 70 million people in Thailand as of 2024. Moreover, most Thais in the northern (Lanna), the Southern (Tai) and the northeastern (Isan) parts of the country today are bilingual speakers of Central Thai and their respective regional dialects because Central Thai is the language of television, education, news reporting, and all forms of media. A recent research found that the speakers of the Northern Thai language (also known as Phasa Mueang or Kham Mueang) have become so few, as most people in northern Thailand now invariably speak Standard Thai, so that they are now using mostly Central Thai words and only seasoning their speech with the "Kham Mueang" accent. Standard Thai is based on the register of the educated classes by Central Thai and ethnic minorities in the area along the ring surrounding the Metropolis.
In addition to Central Thai, Thailand is home to other related Tai languages. Although most linguists classify these dialects as related but distinct languages, native speakers often identify them as regional variants or dialects of the "same" Thai language, or as "different kinds of Thai". As a dominant language in all aspects of society in Thailand, Thai initially saw gradual and later widespread adoption as a second language among the country's minority ethnic groups from the mid-late Ayutthaya period onward. Ethnic minorities today are predominantly bilingual, speaking Thai alongside their native language or dialect.
Standard Thai is classified as one of the Chiang Saen languagesâÂÂothers being Northern Thai, Southern Thai and numerous smaller languages, which together with the Northwestern Tai and Lao-Phutai languages, form the Southwestern branch of Tai languages. The Tai languages are a branch of the KraâÂÂDai language family, which encompasses a large number of indigenous languages spoken in an arc from Hainan and Guangxi south through Laos and Northern Vietnam to the Cambodian border.
Standard Thai is the principal language of education and government and spoken throughout Thailand. The standard is based on the dialect of the central Thai people, and it is written in the Thai script.
Thai has undergone various historical sound changes. Some of the most significant changes occurred during the evolution from Old Thai to modern Thai. The Thai writing system has an eight-century history and many of these changes, especially in consonants and tones, are evidenced in the modern orthography.
According to a Chinese source, during the Ming dynasty, Yingya Shenglan (1405âÂÂ1433), Ma Huan reported on the language of the XiÃÂnluó (æ¹羠) or Ayutthaya Kingdom, saying that it somewhat resembled the local patois as pronounced in Guangdong Ayutthaya, the old capital of Thailand from 1351 - 1767 A.D., was from the beginning a bilingual society, speaking Thai and Khmer. Bilingualism must have been strengthened and maintained for some time by the great number of Khmer-speaking captives the Thais took from Angkor Thom after their victories in 1369, 1388 and 1431. Gradually toward the end of the period, a language shift took place. Khmer fell out of use. Both Thai and Khmer descendants whose great-grand parents or earlier ancestors were bilingual came to use only Thai. In the process of language shift, an abundance of Khmer elements were transferred into Thai and permeated all aspects of the language. Consequently, the Thai of the late Ayutthaya Period which later became Ratanakosin or Bangkok Thai, was a thorough mixture of Thai and Khmer. There were more Khmer words in use than Tai cognates. Khmer grammatical rules were used actively to coin new disyllabic and polysyllabic words and phrases. Khmer expressions, sayings, and proverbs were expressed in Thai through transference.
Thais borrowed both the Royal vocabulary and rules to enlarge the vocabulary from Khmer. The Thais later developed the royal vocabulary according to their immediate environment. Thai and Pali, the latter from Theravada Buddhism, were added to the vocabulary. An investigation of the Ayutthaya Rajasap reveals that three languages, Thai, Khmer and Khmero-Indic were at work closely both in formulaic expressions and in normal discourse. In fact, Khmero-Indic may be classified in the same category as Khmer because Indic had been adapted to the Khmer system first before the Thai borrowed.
Old Thai had a three-way tone distinction on "live syllables" (those not ending in a stop), with no possible distinction on "dead syllables" (those ending in a stop, i.e. either or the glottal stop that automatically closes syllables otherwise ending in a short vowel).
There was a two-way voiced vs. voiceless distinction among all fricative and sonorant consonants, and up to a four-way distinction among stops and affricates. The maximal four-way occurred in labials () and denti-alveolars (); the three-way distinction among velars () and palatals (), with the glottalized member of each set apparently missing.
The major change between old and modern Thai was due to voicing distinction losses and the concomitant tone split. This may have happened between about 1300 and 1600 CE, possibly occurring at different times in different parts of the Thai-speaking area. All voicedâÂÂvoiceless pairs of consonants lost the voicing distinction:
However, in the process of these mergers, the former distinction of voice was transferred into a new set of tonal distinctions. In essence, every tone in Old Thai split into two new tones, with a lower-pitched tone corresponding to a syllable that formerly began with a voiced consonant, and a higher-pitched tone corresponding to a syllable that formerly began with a voiceless consonant (including glottalized stops). An additional complication is that formerly voiceless unaspirated stops/affricates (original ) also caused original tone 1 to lower, but had no such effect on original tones 2 or 3.
The above consonant mergers and tone splits account for the complex relationship between spelling and sound in modern Thai. Modern "low"-class consonants were voiced in Old Thai, and the terminology "low" reflects the lower tone variants that resulted. Modern "mid"-class consonants were voiceless unaspirated stops or affricates in Old ThaiâÂÂprecisely the class that triggered lowering in original tone 1 but not tones 2 or 3. Modern "high"-class consonants were the remaining voiceless consonants in Old Thai (voiceless fricatives, voiceless sonorants, voiceless aspirated stops). The three most common tone "marks" (the lack of any tone mark, as well as the two marks termed mai ek and mai tho) represent the three tones of Old Thai, and the complex relationship between tone mark and actual tone is due to the various tonal changes since then. Since the tone split, the tones have changed in actual representation to the point that the former relationship between lower and higher tonal variants has been completely obscured. Furthermore, the six tones that resulted after the three tones of Old Thai were split have since merged into five in standard Thai, with the lower variant of former tone 2 merging with the higher variant of former tone 3, becoming the modern "falling" tone.
Early Old Thai also apparently had velar fricatives as distinct phonemes. These were represented by the now-obsolete letters kho khuat and kho khon, respectively. During the Old Thai period, these sounds merged into the corresponding stops , and as a result the use of these letters became unstable.
At some point in the history of Thai, an alveolo-palatal nasal phoneme also existed, inherited from Proto-Tai. A letter à ¸ yo ying also exists, which is used to represent an alveolo-palatal nasal in words borrowed from Sanskrit and Pali, and is currently pronounced at the beginning of a syllable but at the end of a syllable. Most native Thai words that are reconstructed as beginning with are also pronounced in modern Thai, but generally spelled with à ¸¢ yo yak, which consistently represents . This suggests that > in native words occurred in the pre-literary period. It is unclear whether Sanskrit and Pali words beginning with were borrowed directly with a , or whether a was re-introduced, followed by a second change > . The northeastern Thai dialect Isan and the Lao language still preserve the phoneme /ò/, which is represented in the Lao script by , such as in the word (, mosquito). This letter is distinct from the phoneme and its Lao letter , such as in the word (, medicine). The distinction in writing has been lost in the informal writing of the Isan language with the Thai script and both sounds are represented by .
Proto-Tai also had a glottalized palatal sound, reconstructed as in Li Fang-Kuei (1977). Corresponding Thai words are generally spelled à ¸«à ¸¢, which implies an Old Thai pronunciation of (or ), but a few such words are spelled à ¸Âà ¸¢, which implies a pronunciation of and suggests that the glottalization may have persisted through to the early literary period.
The vowel system of modern Thai contains nine pure vowels and three centering diphthongs, each of which can occur short or long. According to Li (1977), however, many Thai dialects have only one such shortâÂÂlong pair (), and in general it is difficult or impossible to find minimal shortâÂÂlong pairs in Thai that involve vowels other than and where both members have frequent correspondences throughout the Tai languages. More specifically, he notes the following facts about Thai:
Furthermore, the vowel that corresponds to short Thai has a different and often higher quality in many of the Tai languages compared with the vowel corresponding to Thai .
This leads Li to posit the following:
Not all researchers agree with Li. Pittayaporn (2009), for example, reconstructs a similar system for Proto-Southwestern-Tai, but believes that there was also a mid back unrounded vowel (which he describes as ), occurring only before final velar . He also seems to believe that the Proto-Southwestern-Tai vowel length distinctions can be reconstructed back to similar distinctions in Proto-Tai.
Standard Thai distinguishes three voice-onset times among plosive and affricate consonants:
Whereas English makes a distinction between voiced and voiceless aspirated , Thai distinguishes a third type of voicing, with unaspirated that occurs in English only as an allophone of , for example after an as in the sound of the p in "spin". There is similarly a laminal denti-alveolar , , triplet in Thai. In the velar series there is a , pair and in the postalveolar series a , pair, without the corresponding voiced sounds and . (In loanwords from English, English and are borrowed as the tenuis stops and .) Among some younger speakers (such as younger female speakers from Bangkok metropolian area), postalveolar series are alveolar and . Among some older speakers (such as older speakers from Maeklong river basin), they can be stops and , however this pronunciation is not standard. Voiced stops tend to vary from fully pulmonic to implosives. However, implosive pronunciation is rare among younger speakers due to standardization and influence of the standard dialect.
In each cell below, the first line indicates (IPA), the second indicates the Thai characters in initial position. Note that several letters appearing in the same box have identical pronunciation. In such cases, one of the letters may serve as the "default", being more common and/or preferred for borrowings from English and such; for example, à ¸ in the case of "n" and à ¸ª for "s". The letter à ¸«, the default "h" letter, is also used to help write certain tones (described below).
As with many languages, there is a difference in the number of possibilities for coda consonants in Thai as compared to onset consonants. In Standard Thai, only nine consonants occur in coda position: /p t k àm n à  j w/. Additionally, all plosive sounds are unreleased, so that syllable-final /p t k/ are pronounced as , , and respectively.
Of the consonant letters, excluding the disused à ¸ and à ¸ , six (à ¸ à ¸ à ¸ à ¸« à ¸ à ¸®) cannot be used as a final and the other 36 are grouped as following.
In Thai, the maximal syllable shape is CCVC. In the core vocabulary (i.e. excluding loanwords), only clusters of two consonants occur, of which there are 11 combinations:
The number of clusters increases in loanwords such as (à ¸Âà ¸£) in (, from Sanskrit indrÃÂ) or (à ¸Âà ¸£) in (, from English free); however, these usually only occur in initial position, with either , , or as the second consonant sound and not more than two sounds at a time. In addition, à ¸ may be Romanized as "g" and à ¸ as "b" in those specific clusters to distinguish them from the corresponded aspirated stops.
The vowel nuclei of the Thai language are given in the following table. The top entry in every cell is the symbol from the , the second entry gives the spelling in the Thai script, where a dotted circle (âÂÂ) indicates the position of the initial consonant after which the vowel is pronounced. A second dotted circle indicates that a final consonant follows.
Each vowel quality occurs in longâÂÂshort pairs: these are distinct phonemes forming distinct words in Thai.
The longâÂÂshort pairs are as follows:
There are also opening and closing diphthongs in Thai, which analyze as and . For purposes of determining tone, those marked with an asterisk are sometimes classified as long:
Additionally, there are three triphthongs. For purposes of determining tone, those marked with an asterisk are sometimes classified as long:
There are five phonemic tones: mid, low, falling, high, and rising, sometimes referred to in older reference works as rectus, gravis, circumflexus, altus, and demissus, respectively. The table shows an example of both the phonemic tones and their phonetic realization, in the IPA. Moren & Zsiga (2006) and Zsiga & Nitisaroj (2007) provide phonetic and phonological analyses of Thai tone realization.
Notes:
In some English loanwords, closed syllables with a long vowel ending in an obstruent sound have a high tone, and closed syllables with a short vowel ending in an obstruent sound have a falling tone.
From the perspective of linguistic typology, Thai can be considered an analytic language. The word order is subjectâÂÂverbâÂÂobject, although the subject is often omitted. Additionally, Thai is an isolating language lacking any form of inflectional morphology whatsoever. Thai pronouns are selected according to the gender and relative status of speaker and audience.
There is no morphological distinction between adverbs and adjectives. Many words can be used in either function. They follow the word they modify, which may be a noun, verb, or another adjective or adverb.
Comparatives take the form "A X B" (, ), 'A is more X than B'. The superlative is expressed as "A X " (, ), 'A is most X'.
Adjectives in Thai can be used as complete predicates. Because of this, many words used to indicate tense in verbs (see Verbs:Tense below) may be used to describe adjectives.
Verbs do not inflect. They do not change with person, tense, voice, mood, or number; nor are there any participles. The language being analytic and case-less, the relationship between subject, direct and indirect object is conveyed through word order and auxiliary verbs. Transitive verbs follow the pattern subject-verb-object.
In order to convey tense, aspect and mood (TAM), the Thai verbal system employs auxiliaries and verb serialization. TAM markers are however not obligatory and often left out in colloquial use. In such cases, the precise meaning is determined through context. This results in sentences lacking both TAM markers and overt context being ambiguous and subject to various interpretations.
The sentence can thus be interpreted as 'I am eating there', 'I eat there habitually', 'I will eat there' or 'I ate there'. Aspect markers in Thai have been divided into four distinct groups based on their usage. These markers could appear either before or after the verb. The following list describes some of the most commonly used aspect markers. A number of these aspect markers are also full verbs on their own and carry a distinct meaning. For example () as a full verb means 'to stay, to live or to remain at'. However, as an auxiliary it can be described as a temporary aspect or continuative marker.
The imperfective aspect marker (, , currently) is used before the verb to denote an ongoing action (similar to the -ing suffix in English). is commonly interpreted as a progressive aspect marker. Similarly, (, ) is a post-verbal aspect marker which corresponds to the continuative or temporary aspect.
Comparably, (, , still) is used in an incomplete action, and usually collocates with () or any second marker in common use.
The marker (, ) is usually analyzed as a past tense marker when it occurs before the verb. As a full verb, means 'to get or receive'. However, when used after a verb, takes on a meaning of potentiality or successful outcome of the main verb.
(, ; 'already') is treated as a marker indicating the perfect aspect. That is to say, marks the event as being completed at the time of reference. has two other meanings in addition to its use as a TAM marker. can either be a conjunction for sequential actions or an archaic word for 'to finish'.
Future can be indicated by (, ; 'will') before the verb or by a time expression indicating the future. For example:
Dative marker (, ; 'give') often used in a sentence to indicate prepositional or double objects.
The passive voice is indicated by the insertion of (, ) before the verb. For example:
The construction is traditionally an adversative passive, a feature common to many Southeast Asian languages where a passive construction is restricted to unfavorable meanings (e.g. "he was killed" but not "he was rewarded"), but in current usage is found with virtually all transitive verbs. This neutral usage first arose as an Anglicism as Thailand became Westernized in the early 20th century, but has since become pervasive. The adversative passive persists in the similar construction with (, ).
Negation is indicated by placing (, ; not) before the verb.
Thai exhibits serial verb constructions, where verbs are strung together. Some word combinations are common and may be considered set phrases.
Nouns are uninflected and have no gender; there are no articles. Thai nouns are bare nouns and can be interpreted as singular, plural, definite or indefinite. Some specific nouns are reduplicated to form collectives: (, 'child') is often repeated as () to refer to a group of children. The word (, ) may be used as a prefix of a noun or pronoun as a collective to pluralize or emphasise the following word. (, , , 'we', masculine; , , emphasised 'we'; , '(the) dogs'). Plurals are expressed by adding classifiers, used as measure words (), in the form of noun-number-classifier:
While in English, such classifiers are usually absent ("four chairs") or optional ("two bottles of beer" or "two beers"), a classifier is almost always used in Thai (hence "chair four item" and "beer two bottle").
Possession in Thai is indicated by adding the word () in front of the noun or pronoun, but it may often be omitted. For example:
Nominal phrases in Thai often use a special class of words classifiers. As previously mentioned, these classifiers are obligatory for noun phrases containing numerals e.g.
Unlike any numeral, ('one') can mark on both positions of classifier, but in different functions. The post-head one potentially marks a referent as indefinite article.
In the previous example () acts as the classifier in the nominal phrase. This follows the form of noun-cardinal-classifier mentioned above. Classifiers are also required to form quantified noun phrases in Thai with some quantifiers such as ('all'), ('some'). The examples below are demonstrated using the classifier , which is used for people.
However, classifiers are not utilized for negative quantification. Negative quantification is expressed by the pattern (, ) + NOUN.
Thai has a three-way distinction for its demonstratives: proximal (, ; 'this/these'), medial (, ; 'that/those'), and distal (, ; 'that/those over there') which is rarely used. The tone is changed depending on usage: as a pronoun, the proximal demonstrative is (, ); while (, ) is a modifier placed after nouns, prepositions, classifiers, etc. For example:
The word (, ) plays the role of an interrogative determiner or pronoun.
The syntax for demonstrative phrases, however, differ from that of cardinals and follow the pattern noun-classifier-demonstrative. For example, the noun phrase "this dog" would be expressed in Thai as (literally 'dog (classifier) this').
Subject pronouns are often omitted, with nicknames used where English would use a pronoun. See Thai name#Nicknames for more details. Pronouns, when used, are ranked in honorific registers, and may also make a TâÂÂV distinction in relation to kinship and social status. Specialised pronouns are used for royalty, and for Buddhist monks. The following are appropriate for conversational use:
The reflexive pronoun is (), which can mean any of: myself, yourself, ourselves, himself, herself, themselves. This can be mixed with another pronoun to create an intensive pronoun, such as (, lit: I myself) or (, lit: you yourself). Thai also does not have a separate possessive pronoun. Instead, possession is indicated by the particle (). For example, "my mother" is (, lit: mother of I). This particle is often implicit, so the phrase is shortened to (). Plural pronouns can be easily constructed by adding the word () in front of a singular pronoun as in () meaning 'they' or () meaning the plural sense of 'you'. The only exception to this is (), which can be used as singular (informal) or plural, but can also be used in the form of (), which is only plural.
Thai has many more pronouns than those listed above. Their usage is full of nuances. For example:
The particles are often untranslatable words added to the end of a sentence to indicate respect, a request, encouragement or other moods (similar to the use of intonation in English), as well as varying the level of formality. They are not used in elegant (written) Thai. The most common particles indicating respect are (, , with a high tone) when the speaker is a man, and (, , with a falling tone) when the speaker is a woman. Used in a question or a request, the particle (falling tone) is changed to a (high tone).
Other common particles are:
Central Thai is composed of several distinct registers, forms for different social contexts:
Most Thais can speak and understand all of these contexts. Street and Elegant Thai are the basis of all conversations. Rhetorical, religious, and royal Thai are taught in schools as part of the national curriculum.
As noted above, Thai has several registers, each having certain usages, such as colloquial, formal, literary, and poetic. Thus, the word 'eat' can be (; common), (; vulgar), (; vulgar), (; formal), (; formal), (; religious), or (; royal), as illustrated below:
Thailand also uses the distinctive Thai six-hour clock in addition to the 24-hour clock.
Other than compound words and words of foreign origin, most words are monosyllabic.
Chinese-language influence was strong until the 13th century when the use of Chinese characters was abandoned, and replaced by Sanskrit and Pali scripts. However, the vocabulary of Thai retains many words borrowed from Middle Chinese.
Khmer was used as a prestige language in the early days of the Thai kingdoms which are believed to have been bilingual societies proficient in Thai and Khmer. There are over 2,500 Thai words derived from Khmer, surpassing the number of Tai cognates. These Khmer words span across all semantic fields. Thai scholar Uraisi Varasarin classified them into over 200 sub-categories. As a result, it is impossible for Thais, past and present, to engage in a conversation without incorporating Khmer loanwords in any given topic. The influence is particularly preponderant in regard to royal court terminology.
Later, most vocabulary was borrowed from Sanskrit and PÃÂli; Buddhist terminology is particularly indebted to these. Indic words have a more formal register, and may be compared to Latin and French borrowings in English. Since the beginning of the 20th century, however, the English language has had the greatest influence, especially for scientific, technical, international, and other modern terms.
From Middle Chinese or Teochew Chinese.
From Old Khmer
The Portuguese were the first Western nation to arrive in what is modern-day Thailand in the 16th century during the Ayutthaya period. Their influence in trade, especially weaponry, allowed them to establish a community just outside the capital and practise their faith, as well as exposing and converting the locals to Christianity. Thus, Portuguese words involving trade and religion were introduced and used by the locals.
Thai is written in the Thai script, an abugida written from left to right. The language and its script are closely related to the Lao language and script. Most literate Lao are able to read and understand Thai, as more than half of the Thai vocabulary, grammar, intonation, vowels and so forth are common with the Lao language.
The Thais adopted and modified the Khmer script to create their own writing system. While in Thai the pronunciation can largely be inferred from the script, the orthography is complex, with silent letters to preserve original spellings and many letters representing the same sound. While the oldest known inscription in the Khmer language dates from 611 CE, inscriptions in Thai writing began to appear around 1292 CE. Notable features include:
There is no universally applied method for transcribing Thai into the Latin alphabet. For example, the name of the main airport is transcribed variably as Suvarnabhumi, Suwannaphum, or Suwunnapoom. Guide books, textbooks and dictionaries follow different systems. For this reason, many language courses recommend that learners master the Thai script.
Official standards are the Royal Thai General System of Transcription (RTGS), published by the Royal Institute of Thailand, and the almost identical defined by the International Organization for Standardization. The RTGS system is increasingly used in Thailand by central and local governments, especially for road signs. Its main drawback is that it does not indicate tone or vowel length. As the system is based on pronunciation, not orthography, reconstruction of Thai spelling from RTGS romanisation is not possible.
The ISO published an international standard for the transliteration of Thai into Roman script in September 2005 (ISO 11940). By adding diacritics to the Latin letters it makes the transcription reversible, making it a true transliteration. Notably, this system is used by Google Translate, although it does not seem to appear in many other contexts, such as textbooks and other instructional media.
Article 1 of the Universal Declaration of Human Rights in Thai:
Transliteration:
Article 1 of the Universal Declaration of Human Rights in English: