Thai,In or Central Thai (historically Siamese;Although "Thai" and "Central Thai" have become more common, the older term, "Siamese", is still used by linguists, especially when it is being distinguished from other Tai languages (Diller 2008:6). "Proto-Thai" is, for example, the ancestor of all of Southwestern Tai, not just Siamese (Rischel 1998). ), is a Tai language of the Kra–Dai language family. It is spoken by the Central Thai, Mon, Lao Wiang, and Phuan people in Central Thailand and by 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. Central Thai is the language of television, education, news reporting, and all forms of media. Most Thais in the northern (Lanna), the Southern (Tai) and the northeastern (Isan) parts of the country are therefore today bilingual in Central Thai and their own regional dialect. A study found that speakers of the Northern Thai language, also known as Phasa Mueang or Kham Mueang, have become few, most people in northern Thailand now speaking Standard Thai. They use mostly Central Thai words and only season 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.
Classification
Standard Thai is classified as one of the Chiang Saen languages, the others 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 Kra–Dai 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.
History 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.
Early spread According to the Ming dynasty Chinese source Yingya Shenglan (1405–1433) written by Ma Huan, the language of the Xiānluó (暹羅) or Ayutthaya Kingdom somewhat resembled the local patois pronounced in Guangdong. Ayutthaya, the capital of Thailand from 1351 to 1767 CE, was a bilingual society from its inception where both Thai and Khmer were spoken. This bilingualism was likely strengthened and maintained by the large number of Khmer-speaking captives the Thais relocated from Angkor Thom following their military victories in 1369, 1388, and 1431.
Toward the end of the Ayutthaya period Khmer fell out of everyday use and a language shift took place. Descendants of bilingual families came to use only Thai. Many Khmer elements passed into Thai during the shift, reaching every part of the language. The Thai of the late Ayutthaya period, which later became Rattanakosin or Bangkok Thai, was a thorough mixture of Thai and Khmer, with more Khmer words in use than Tai cognates. Khmer grammatical rules were used to coin new disyllabic and polysyllabic words and phrases, and Khmer expressions, sayings and proverbs were taken into Thai directly.
Thais borrowed and expanded their royal vocabulary (rajasap) using Khmer rules. They then developed it to suit their own cultural environment, drawing on Thai and on Pali, which came with Theravada Buddhism. An analysis of the Ayutthaya royal vocabulary found three elements, Thai, Khmer and Khmero-Indic, working closely together in formulaic expressions and in ordinary discourse. Because Indic elements had entered Khmer before Thai borrowed them, Khmero-Indic can be classified with Khmer.
The Mon contribution is harder to establish. Mathias Jenny holds that nothing conclusive can be said at the present state of research about structural Mon influence on Thai. He points instead to Christian Bauer's work on features of early Thai inscriptions and on lexical and grammatical items putatively borrowed from Mon. Where the evidence does not settle which language borrowed from which, as with dàan 'path' and sàphaan 'bridge', he leaves the direction open.
Bauer dated two of those loans from the sound changes each had to pass through. Thorahot () 'tough, unyielding' comes from Old Mon dirhat, and entered Thai no earlier than the 12th century and no later than the 15th. Thayae (), a kind of song, is a Middle Mon loan that cannot have been taken up before the 13th century, which suggested to Bauer that Thai still had a voicing distinction after that date. The two donor languages can be hard to tell apart. Griswold and Prasert ṇa Nagara took karayā (), attested in an inscription of 1357, as a borrowing from Khmer; Bauer proposed Old Mon instead, allowing that the early Thai form his reading requires is still to be established. A Khmer loan in the same inscription, parayana from Old Khmer paryyan, shows the same syllabified cluster in Early Thai. A second word is dated by its first appearance in the inscriptions. 'vessel, cup, for offerings' appears in 1369, spelt , and Bauer took it from Old Mon khal. He reports that Michel Ferlus, in conversation, preferred Old Khmer khan, and answers that no variation in vowel length is attested for the word in Khmer and none in Early Thai epigraphy.
Five of the eleven loans Bauer treats are grammatical markers, and one of the remaining six belongs to the core vocabulary. One of the eleven he assigned to Khmer rather than Mon, 'especially', from Khmer chboḥ, attested in Middle Khmer. One he would not decide. occurs in the Sukhothai corpus only in inscription 38, where the same text spells it three ways, and he held that its origin cannot be determined beyond its being either Khmer or Mon, the word having become obsolete in both. A core-vocabulary loan of the same kind is /tham/. Bauer took it and /kraʔtham/ for doublets borrowed from Old Mon kindaṁ, attested since the 7th century and glossed by Shorto 'to perform, build, construct, make; rebuild'. Neither the simple base he reconstructs behind it nor its root is attested in Mon, and he argued for that base from a spoken Mon reflex of a related noun. Among the grammatical items he assigns to Mon is /chaʔ/ (), in /chaʔ nán/ () and /chaʔ níː/ () 'so, then, consequently'. He claims it for a Mon form that Shorto classes as a noun and that is attested only from Middle Mon in 1480. He reads /phrɔʔ chaʔ nán/ () as a blend of Khmer /pruəh/ 'because' with the same element. The form is not attested in Epigraphic Thai.
The case Bauer makes for Mon influence beyond the lexicon rests on a single word. Early Thai sadāṁ, which occurs once in the whole Sukhothai corpus, he read as a blend of the Old Mon prefix s-, which marks the hypothetical, with Early Thai dāṁ. That verb is itself a doublet, borrowed from a Mon form attested only as the frequentative kindaṁ. At that one attestation the verb carries two markers of the same category, Early Thai cakk before it and the Mon prefix on it, which he took for interference rather than convergence. He set out seven environments in which the Mon prefix and cakk follow the same rule and called them an identical set of syntactic restrictions. He reached the Mon reading by elimination. No form in si-, sa- or s- is attested anywhere in the Thai epigraphic corpus, which rules out a Thai prefix, and a fossilised Mon cluster would have left a different Thai form. That negative rests on the whole Sukhothai corpus and on the north-eastern Thai corpus, and he noted that inscriptions from northern Thailand had not been comprehensively examined. Because the prefix occurs nowhere else, he suggested that the first language of that one writer may not have been Thai but Mon. He also displaced an explanation of Griswold and Prasert ṇa Nagara's. They had put the long periodic sentences of a Sukhothai inscription down to Maha Thammaracha I's familiarity with Sanskrit and Pali. Bauer answered that the same stacking of clauses is frequent in Old Mon and unknown in Khmer.
Old Thai Sample from the Ramkhamhaeng SteeleSukhothai ScriptModern Thai TranscribedIPA SukhothaiMeaningพ่กูชื่สรีอีนทราทีตยแม่กูชื่นางเสือง พี่กูชื่บานเมืองตูพี่น้องท้องดยว
ห้าคนผู้ชายสามผู้ญิงโสงพี่เผือ
ผู้อ้ายตายจากเผือตยมแฏ่ญงงเลกbɔː˩ kuː dʑɯː˩ siː.ʔiːn.draː.diːt mɛː˩ kuː dʑɯː˩ naːŋ sɯaŋ
biː˩ kuː dʑɯː˩ baːn.mɯaŋ
tuː biː˩ nɔːŋ˥ dɔːŋ˥ ʔdiaw haː˥ gɔn
pʰuː˥.dʑaːj saːm pʰuː˥.ɲiŋ soːŋ
biː˩ pʰɯa pʰuː˥.ʔaːj˥ taːj tɕaːk
pʰɯa tiam tɛː˩ ɲaŋ lek .....My father's name is Sri Indraditya, My mother's name is lady Sueang.
My older brother's name is Ban Mueang.
We are five siblings from the same womb.
three boys and two girls.
Our eldest brother passed away.
when we were young.... [text continues]Modern Thai Approximate Pronunciation and Transliterationบ่อ กู จื่อ ซีอีนดราดีต แหม่ กู จื่อ นางเซือง บี่ กู จื่อ บานเมือง ตู บี่ น่อง ด้อง เดียว ห้า กอน ผู้จาย ซาม ผู้ญิง โซง บี่ เบือ ผู้อ้าย ตาย จาก เพือ เตียม แต่ ญัง เล็ก bo ku jue Si-Indradit mae ku jue Nang Sueang bi ku jue Ban Mueang tu bi nong dong diao ha gon phujai sam phunying song bi phuea phu-ai tai chak phuea tiam tae nyang lek (voiced stops are approximated as unvoiced in this case due to its absence in modern Thai) Old Thai had a three-way tone distinction on "live syllables" (those not ending in a stop), with no possible tonal 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 versus voiceless distinction among all fricative and sonorant consonants, and up to a four-way distinction among stops and affricates. The maximal four-way distinction occurred in labials () and denti-alveolars (). A three-way distinction existed among velars () and palatals (), with the glottalized member of each set apparently missing.
The major change between Old and modern Thai was driven by the loss of the voicing distinction and the concomitant tone split. This transition likely occurred between 1300 and 1600 CE, possibly happening at different times across different parts of the Thai-speaking area. During this period, all voiced–voiceless pairs of consonants lost their voicing distinction: