Thai language

Thai language

Thai language, formerly Siamese, member of the Tai or Thai subfamily of the Sino-Tibetan family of languages (see Sino-Tibetan languages). The official language of Thailand, Thai is spoken by approximately 50 million people in Thailand, Vietnam, and the Yunnan province of China. It has several dialects. Although most of the words are monosyllables, a number of them are polysyllabic. Because there is no inflection, word order is important for showing grammatical relationships. The Thai language is also tonal, and the tones serve to distinguish meanings of words otherwise pronounced alike. There are five tones: high, middle, low, rising, and falling. Over the centuries Thai has borrowed many words from Chinese, Khmer, Pali, Sanskrit, and, more recently, from European languages such as French and English. The Thai language has its own alphabet, which ultimately goes back to a script of S India and which was adopted in the 13th cent. A.D. Thai is written from left to right.

See E. M. Anthony et al., Foundations of Thai (1968); U. Warotamasikkhadit, Thai Syntax: An Outline (1972); M. R. Haas and H. R. Subhanka, Spoken Thai (1973).

Thai (ภาษาไทย, , transcription: phasa thai, transliteration: ; pʰāːsǎːtʰāj), is the national and official language of Thailand and the mother tongue of the Thai people, Thailand's dominant ethnic group. Thai is a member of the Tai group of the Tai-Kadai language family. The Tai-Kadai languages are thought to have originated in what is now southern China, and some linguists have proposed links to the Austroasiatic, Austronesian, or Sino-Tibetan language families. It is a tonal and analytic language. The combination of tonality, a complex orthography, relational markers and a distinctive phonology can make Thai difficult to learn for those who do not already speak a related language. Thai is mutual intelligible to Lao.

Languages and dialects

Standard Thai, also known as Central Thai or Siamese, is the official language of Thailand, spoken by about 65 million people (1990) including speakers of Bangkok Thai (although the latter is sometimes considered as a separate dialect). Khorat Thai is spoken by about 400,000 (1984) in Nakhon Ratchasima; it occupies a linguistic position somewhere between Central Thai and Isan on a dialect continuum, and may be considered a variant or dialect of either. A majority of the people in the Isan region of Thailand speak a dialect of the Lao language, which has influenced the Central Thai dialect.

In addition to Standard Thai, Thailand is home to other related Tai languages, including:

Statistics are from Ethnologue 2003-10-4

Many of these languages are spoken by larger numbers outside of Thailand. Most speakers of dialects and minority languages speak Central Thai as well, since it is the language used in schools and universities all across the kingdom.

Numerous languages not related to Thai are spoken within Thailand by ethnic minority hill tribespeople. These languages include Hmong-Mien (Yao), Karen, Lisu, and others.

Standard Thai is composed of several distinct registers, forms for different social contexts:

  • Street Thai (ภาษาพูด, spoken Thai): informal, without polite terms of address, as used between close relatives and friends.
  • Elegant Thai (ภาษาเขียน, written Thai): official and written version, includes respectful terms of address; used in simplified form in newspapers.
  • Rhetorical Thai: used for public speaking.
  • Religious Thai: (heavily influenced by Sanskrit and Pāli) used when discussing Buddhism or addressing monks.
  • Royal Thai (ราชาศัพท์): (influenced by Khmer) used when addressing members of the royal family or describing their activities.

Most of the Thais can speak and understand all of these contexts. Street and Elegant are the basis of all conversations, rhetorical, religious and royal Thai are taught in schools as the national curriculum has set so.


The Thai alphabet is derived from the Khmer alphabet, which is modeled after the Brahmic script from the Indic family. The language and its alphabet are closely related to the Lao language and alphabet. Most Laotians 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. Much like the Burmese adopted the Mon script (which also has Indic origins), the Thais adopted and modified Khmer script to create their own writing system. 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:

  1. It is an abugida script, in which the implicit vowel is a short /a/ in a syllable without final consonant and a short /o/ in a syllable with final consonant.
  2. Tone markers are placed above the consonant just before the vowel sound of the syllable.
  3. Vowels sounding after a consonant are nonsequential: they can be located before, after, above or below the consonant, or in a combination of these positions.


There is no universal standard for transcribing Thai into the Latin alphabet. For example, the name of King Rama IX, the present monarch, is transcribed variously as Bhumibol, Phumiphon, phuuM miH phohnM, or many other versions. Guide books, text books and dictionaries may each follow different systems. For this reason, most language courses recommend that learners master the Thai alphabet.

What comes closest to a standard is the Royal Thai General System of Transcription (RTGS), published by the Thai Royal Institute only in Thai at This system is increasingly used in Thailand by central and local governments, especially for road signs. Its main drawbacks are that it does not indicate tone or vowel length. It is not possible to reconstruct the Thai spelling from the RTGS transcriptions.


The ISO published an international standard for the transliteration of Thai into Roman script in September 2003 (ISO 11940) By adding diacritics to the Latin letters, it makes the transcription reversible, making it a true transliteration. This system is intended for academic use and is hardly ever used in Thailand for the common public.


From the perspective of linguistic typology, Thai can be considered to be an analytic language. The word order is Subject Verb Object, although the subject is often omitted. The Thai pronominal system varies according to the sex and relative status of speaker and audience.

Adjectives and adverbs

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. Intensity can be expressed by a duplicated word, which is used to mean "very" (with the first occurrence at a higher pitch) or "rather" (with both at the same pitch) (Higbie 187-188). Usually, only one word is duplicated per clause.

  • คนอ้วน (khon uan, ) a fat person
  • คนอ้วนๆ (khon uan uan, ) a very/rather fat person
  • คนที่อ้วนเร็วมาก (khon thi uan reo mak) a person who becomes/became fat very quickly
  • คนที่อ้วนเร็วมากๆ (khon thi uan reo mak mak) a person who becomes/became fat very very quickly

Comparatives take the form "A X กว่า B" (kwa, kwaː), A is more X than B. The superlative is expressed as "A X ที่สุด" (thi sut, tʰiːsut), A is most X.

  • เขาอ้วนกว่าฉัน (khao uan kwa chan) S/he is fatter than me.
  • เขาอ้วนที่สุด (khao uan thi sut) S/he is the fattest (of all).

Because adjectives can be used as complete predicates, many words used to indicate tense in verbs (see Verbs:Tense below) may be used to describe adjectives.

  • ฉันหิว (chan hiu) I am hungry.
  • ฉันจะหิว (chan cha hiu) I will be hungry.
  • ฉันกำลังหิว (chan kamlang hiu) I am becoming hungry. or I am hungry right now.
  • ฉันหิวแล้ว (chan hiu laeo) I am already hungry. or I was hungry already.

* Remark ฉันหิวแล้ว mostly means "I am hungry right now" because normally, แล้ว(laeo)is a word used to indicate the past but sometime, it is used for euphony without meaning. For example, แล้วเธอจะไปไหน(laeo thoe cha pai nai): Where will you go?, this sentence แล้ว did not indicate at all, so แล้ว(laeo) is not always to indicate the past.


Verbs do not inflect (i.e. do not change with person, tense, voice, mood, or number) nor are there any participles. Duplication conveys the idea of doing the verb intensively.

The passive voice is indicated by the insertion of ถูก (thuk, tʰuːk)) before the verb. For example:

  • เขาถูกตี (khao thuk ti, ), He is hit. This describes an action that is out of the receiver's control and, thus, conveys suffering.

To convey the opposite sense, a sense of having an opportunity arrive, ได้ (dai, daj, can) is used. For example:

  • เขาจะได้ไปเที่ยวเมืองลาว (khao cha dai pai thiao mueang lao, ), He gets to visit Laos.

Note, dai (daj and daːj), though both spelled ได้ , convey two separate meanings. The short vowel dai (daj) conveys an opportunity has arisen and is placed before the verb. The long vowel dai (daːj) is placed after the verb and conveys the idea that one has been given permission or one has the ability to do something. Also see the past tense below.

  • เขาตีได้ (khao ti dai, ), He is/was allowed to hit or He is/was able to hit

Negation is indicated by placing ไม่ (mai, not) before the verb.

  • เขาไม่ตี, (khao mai ti) He is not hitting. or He doesn't hit.

Tense is conveyed by tense markers before or after the verb.

Present can be indicated by กำลัง (kamlang, kamlaŋ, currently) before the verb for ongoing action (like English -ing form), by อยู่ (yu, juː) after the verb, or by both. For example:
* เขากำลังวิ่ง (khao kamlang wing, ), or
* เขาวิ่งอยู่ (khao wing yu, ), or
* เขากำลังวิ่งอยู่ (khao kamlang wing yu, ), He is running.

Future can be indicated by จะ (cha, tɕaʔ, will) before the verb or by a time expression indicating the future. For example:
* เขาจะวิ่ง (khao cha wing, ), He will run or He is going to run

Past can be indicated by ได้ (dai, daːj) before the verb or by a time expression indicating the past. However, แล้ว (laeo, :lɛːw, already) is more often used to indicate the past tense by being placed behind the verb. Or, both ได้ and แล้ว are put together to form the past tense expression, i.e. Subject + ได้ + Verb + แล้ว. For example:
* เขาได้กิน (khao dai kin, ), He ate
* เขากินแล้ว (khao kin laeo, , He (already) ate or He's already eaten
* เขาได้กินแล้ว (khao dai kin laeo, ), He (already) ate or He's already eaten

Nouns and pronouns

Nouns are uninflected and have no gender; there are no articles.

Nouns are neither singular nor plural. Some specific nouns are reduplicated to form collectives: เด็ก (dek, child) is often repeated as เด็กๆ (dek dek) to refer to a group of children. The word พวก (phuak, [pʰûak]) may be used as a prefix of a noun or pronoun as a collective to pluralize or emphasise the following word. (พวกผม, phuak phom, , we, masculine; พวกเรา phuak rao, , emphasised we; พวกหมา phuak ma, (the) dogs) Plurals are expressed by adding classifiers, used as measure words (ลักษณนาม), in the form of noun-number-classifier (ครูห้าคน, "teacher five person" for "five teachers"). 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").

Subject pronouns are often omitted, while nicknames are often used where English would use a pronoun. There are specialised pronouns in the royal and sacred Thai languages. The following are appropriate for conversational use:

Word RTGS IPA Meaning
ผม phom [pʰǒm] I/me (masculine; formal)
ดิฉัน dichan [dìːtɕʰán]) I/me (feminine; formal)
ฉัน chan [tɕʰǎn] I/me (masculine or feminine; informal)
คุณ khun [kʰun] you (polite)
ท่าน than [tʰâːn] you (polite to a person of high status)
เธอ thoe [tʰɤː] you (informal), she/her (informal)
เรา rao [raw] we/us, I/me (casual)
เขา khao [kʰǎw] he/him, she/her
มัน man [mɑn] it
พวกเขา phuak khao they/them
พี่ phi [pʰîː] older brother, sister (also often used loosely for older cousins and non-relatives)
น้อง nong [nɔːŋ] younger brother, sister (also often used loosely for younger cousins and non-relatives)
ลูกพี่ ลูกน้อง luk phi luk nong cousin (male or female)


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 ครับ (khrap, kʰráp, with a high tone) for a man, and ค่ะ (kha, [kʰâ], with a falling tone) for a woman; these can also be used to indicate an affirmative.

Other common particles are:

Word RTGS IPA Meaning
จ๊ะ cha [tɕaʔ] indicating a request
จ้ะ, จ้า or จ๋า cha [tɕaː] indicating emphasis
ละ or ล่ะ la [laʔ] indicating emphasis
สิ si [siʔ] indicating emphasis or an imperative
นะ na [naʔ] softening; indicating a request



There are five phonemic tones: middle, low, high, rising and falling. The table shows an example of both the phonemic tones and their phonetic realization, in the IPA.
Tone Thai Phonemic Phonetic English
mid นา /nāː/ [naː˥˧] a paddy
low หน่า /nàː/ [naː˧˩] (a nickname)
falling หน้า /nâː/ [naː˥˩] face
high น้า /náː/ [naː˧˥] aunt/uncle(younger than your parents)
rising หนา /nǎː/ [naː˨˩˧] thick


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 /b/ and the unvoiced, aspirated /p/, Thai distinguishes a third sound which is neither voiced nor aspirated, which occurs in English only as an allophone of /p/, approximately the sound of the p in "spin." There is similarly an alveolar /t/, /tʰ/, /d/ triplet. In the velar series there is a /k/, /kʰ/ pair and in the postalveolar series the /tɕ/, /tɕʰ/ pair.

In each cell below, the first line indicates IPA (IPA), the second indicates the Thai characters in initial position (more letters appearing in the same box have identical pronunciation).

  Bilabial Labio-
Alveolar Post-
Palatal Velar Glottal







ฉ, ช, ฌ

* ฑ can be pronounced as [tʰ] or [d] depended on Thai words.
** The glottal plosive is implied after a short vowel without final, or the silent อ before a vowel.


The basic vowels of the Thai language, from front to back and close to open, are given in the following table. The top entry in every cell is the symbol from the IPA, the second entry gives the spelling in the Thai alphabet, where a dash (–) indicates the position of the initial consonant after which the vowel is pronounced. A second dash indicates that a final consonant must follow.

  Front Back
unrounded unrounded rounded
short long short long short long
Close /i/
Close-mid /e/
Open-mid /ɛ/
Open     /a/
-ะ, -ั

The vowels each exist in long-short pairs: these are distinct phonemes forming unrelated words in Thai, but usually transliterated the same: เขา (khao) means he or she, while ขาว (khao) means white.

The long-short pairs are as follows:

Long Short
Thai IPA Gloss Thai script IPA Gloss
–า /aː/ /fǎːn/ 'to slice' –ะ /a/ /fǎn/ 'to dream'
–ี  /iː/ /krìːt/ 'to cut' –ิ  /i/ /krìt/ 'dagger'
–ู  /uː/ /sùːt/ 'to inhale' –ุ  /u/ /sùt/ 'rearmost'
เ– /eː/ /ʔēːn/ 'to recline' เ–ะ /e/ /ʔēn/ 'ligament'
แ– /ɛː/ /pʰɛ́ː/ 'to be defeated' แ–ะ /ɛ/ /pʰɛ́ʔ/ 'goat'
–ื  /ɯː/ /kʰlɯ̂ːn/ 'wave' –ึ  /ɯ/ /kʰɯ̂n/ 'to go up'
เ–อ /ɤː/ /dɤ̄ːn/ 'to walk' เ–อะ /ɤ/ /ŋɤ̄n/ 'silver'
โ– /oː/ /kʰôːn/ 'to fell' โ–ะ /o/ /kʰôn/ 'thick (soup)'
–อ /ɔː/ /klɔːŋ/ 'drum' เ–าะ /ɔ/ /klɔ̀ŋ/ 'box'

The basic vowels can be combined into diphthongs. analyze those ending in high vocoids as underlyingly /Vj/ and /Vw/. For purposes of determining tone, those marked with an asterisk are also classified as long:

Long Short
Thai IPA Thai IPA
–าย /aːj/ ไ–*, ใ–*, ไ–ย /aj/
–าว /aːw/ เ–า* /aw/
เ–ีย /iːa/ เ–ียะ /ia/
–ิว /iw/
–ัว /uːa/ –ัวะ /ua/
–ูย /uːj/ –ุย /uj/
เ–ว /eːw/ เ–็ว /ew/
แ–ว /ɛːw/
เ–ือ /ɯːa/
เ–ย /ɤːj/
–อย /ɔːj/
โ–ย /oːj/

Additionally, there are three triphthongs, all of which are long:

Thai IPA
เ–ียว /iow/
–วย /uɛj/
เ–ือย /ɯɛj/

For a guide to written vowels, see the Thai alphabet page.


Other than compound words and words of foreign origin, most words are monosyllabic. Historically, words have most often been borrowed from Sanskrit and Pāli; Buddhist terminology is particularly indebted to these. Old Khmer has also contributed its share, especially in regard to royal court terminology. Since the beginning of the 20th century, however, the English language has had the greatest influence. Many Teochew Chinese words are also used, some replacing existing Thai words.

Thailand also uses the distinctive Thai six hour clock in addition to the 24 hour clock.



  • Higbie, James and Thinsan, Snea. Thai Reference Grammar: The Structure of Spoken Thai. Bangkok: Orchid Press, 2003. ISBN 974-8304-96-5.
  • Nanthana Ronnakiat, Dr. (นันทนา รณเกียรติ, ดร.) Phonetics in Principle and Practical. (สัทศาสตร์ภาคทฤษฎีและภาคปฏิบัติ) Bangkok: Thammasat University, 2005. ISBN 974-571-929-3.
  • Segaller, Denis. Thai Without Tears: A Guide to Simple Thai Speaking. Bangkok: BMD Book Mags, 1999. ISBN 974-87115-2-8.
  • Smyth, David. Thai: An Essential Grammar. London: Routledge, 2002. ISBN 0-415-22614-7.

See also

External links

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