Thai ( Phasa Thai, ) 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 Kradai language family. The Kradai languages are thought to have originated in what is now southern China. Historical linguists have been unable to definitively link the Kradai languages to any other language family. Many words in Thai are borrowed from Pali, Sanskrit and Old Khmer. It is a tonal and analytic language. Thai also has a complex orthography and relational markers. Thai is mutually intelligible with 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 the 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:

• Isan (Northeastern Thai), the language of the Isan region of Thailand, a socio-culturally distinct Thai-Lao hybrid dialect which is written with the Thai alphabet. It is spoken by about 15 million people (1983).

• Nyaw language, spoken mostly in Nakhon Phanom Province, Sakhon Nakhon Province, Udon Thani Province of Northeast Thailand.

• Galung language, spoken in Nakhon Phanom Province of Northeast Thailand.

• Lü (Tai Lue, Dai), spoken by about 78,000 (1993) in northern Thailand.

• Northern Thai (Phasa Nuea, Lanna, Kam Mueang, or Thai Yuan), spoken by about 6 million (1983) in the formerly independent kingdom of Lanna (Chiang Mai).

• Phuan, spoken by an unknown number of people in central Thailand, Isan and Northern Laos.

• Phu Thai, spoken by about 156,000 around Nakhon Phanom Province (1993).

• Shan (Thai Luang, Tai Long, Thai Yai), spoken by about 56,000 in north-west Thailand along the border with the Shan States of Burma (1993).

• Song, spoken by about 20,000 to 30,000 in central and northern Thailand (1982).

• Southern Thai (Phasa Tai), spoken about 5 million (1990).

• Thai Dam, spoken by about 20,000 (1991) in Isan and Saraburi Province.

Statistics are from .
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.

Script

Many scholars believe that the Thai alphabet is derived from the Khmer alphabet, which is modeled after the Brahmic script from the Indic family. However, in appearance, Thai is closer to Thai Dam script, which may have the same Indian origins as Khmer script. The language and its alphabet are closely related to the Lao language and alphabet. 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.
Much like the Burmese adopted the Mon script (which also has Indic origins), the Thais adopted and modified the 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:

• 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.

• Tone markers are placed above the consonant just before the vowel sound of the syllable.

• 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.

Transcription

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, phuu^M mi^H phohn^M, 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. 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.

Transliteration

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, but is rarely used in any context.

Grammar

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. Thai pronouns are selected according to the gender 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, ), A is more X than B. The superlative is expressed as "A X ที่สุด" (thi sut, ), 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 hungry right now.

• ฉันหิวแล้ว (chan hiu laeo) I am already hungry.

Verbs

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, )) 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, , can) is used. For example:

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

Note, dai ( and ), though both spelled ได้ , convey two separate meanings. The short vowel dai () conveys an opportunity has arisen and is placed before the verb. The long vowel dai () 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.



Thai exhibits serial verb construction, where verbs are stringed together. Some word combinations are common and may be considered set phrases.

• เขาไปกินข้าว (khao pai kin khao) He went out to eat, literally He go eat food

• ฉันฟังไม่เข้าใจ (chun fung mai khao chai) I don't understand what was said, literally I listen not understand

• เข้ามา (khao ma) Come in, literally enter come

• ออกไป! (ok pai) Leave! or Get out!, literally exit go

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, ) 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:

The reflexive pronoun is ตัวเอง (tua eng), 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 ตัวผมเอง (tua phom eng, lit: I myself)
or ตัวคุณเอง (tua khun eng, lit: you yourself).

Thai does not have a separate possessive pronoun. Instead, possession is indicated by the particle ของ (khong). For example, "my mother" is แม่ของผม (mae khong phom, lit: mother of I). This particle is often implicit, so the phrase is shortened to แม่ผม (mae phom).

Above is only a short list. Thai language has many more pronouns. Their usage is full of nuances. For example:

• "ผม เรา ฉัน ดิฉัน ชั้น หนู กู ข้า กระผม ข้าพเจ้า กระหม่อม อาตมา" all translate to "I", but each word expresses different gender, age, politeness, status, and relationship between the speaker and listener.

• เรา (rao) can be first person (I), second person (you), or both (we), depending on the context.

• When speaking to someone older, หนู (nu) is a feminine first person (I). However, when speaking to someone younger, the same word หนู is a neuter second person (you).

• The second person pronoun เธอ (thoe) (lit: you) is semi-feminine. It is used only when the speaker or the listener (or both) are female. Males usually don't address each other by this pronoun.

• Both คุณ (khun) and เธอ (thoe) are polite neuter second person pronouns. However, คุณเธอ (khun thoe) is a feminine derogative third person.

• Instead of a second person pronoun such as "คุณ" (you), it's much more common for unrelated strangers to call each other "พี่ น้อง ลุง ป้า น้า อา ตา ยาย" (brother/sister/aunt/uncle/granny).

• To express deference, the second person pronoun is sometimes replaced by a profession, similar to how, in English, presiding judges are always addressed as "your honor" rather than "you". In Thai, students always address their teachers by "ครู คุณครู อาจารย์" (each means teacher) rather than คุณ (you). Teachers, monks, and doctors are almost always addressed this way.

Particles

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, , with a high tone) for a man, and ค่ะ (kha, , with a falling tone) for a woman; these can also be used to indicate an affirmative, though the ค่ะ (falling tone) is changed to a คะ (high tone).

Other common particles are:

Phonology

Tones

There are five phonemic tones: middle, low, falling, high and rising, sometimes referred to in older reference works as rectus, circumflexus, gravis, altus and demissus, respectively. The table shows an example of both the phonemic tones and their phonetic realization, in the IPA.

Consonants

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 an alveolar , , triplet. In the velar series there is a , pair and in the postalveolar series the , pair.

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

Vowels

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 International Phonetic Alphabet, 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.

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:

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

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

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

Vocabulary

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.

See also

• Thai numerals

• Literature in Thailand

• The Royal Institute of Thailand