|ภาษาไทย phasa thai|
|Ethnicity||Central Thai and Thai Chinese as monolingual|
20 million (2000; monolingual)
40 million bilingual with Lanna, Isan, Southern Thai or Northern Khmer (2001)
Official language in
|Regulated by||The Royal Institute|
Thai, or more precisely Siamese or Central Thai, is the national and official language of Thailand and the native language of the Thai people and Thai Chinese. Thai is a member of the Tai group of the Tai–Kadai language family. Over half of the 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.
Dialects and related languages 1
- Related languages 1.1
- Registers 1.2
- Transcription 2.1
- Transliteration 2.2
- Initials 3.1.1
- Finals 3.1.2
- Clusters 3.1.3
- Vowels 3.2
- Unchecked syllables 3.3.1
- Checked syllables 3.3.2
- Consonants 3.1
- Adjectives and adverbs 4.1
- Verbs 4.2
- Nouns 4.3
- Pronouns 4.4
- 4.5 Particles
- Vocabulary 5
- Old Thai 6.1
- Vowel developments 6.2
- See also 7
- Notes 8
- References 9
- External links 10
Thai is the official language of Thailand, spoken by over 20 million people (2000), Standard Thai is based on the register of the educated classes of Bangkok. In addition to Central Thai, Thailand is home to other related Tai languages. Although linguists usually classify these idioms as related, but distinct languages, native speakers often identify them as regional variants of the "same" Thai language, or as "different kinds of Thai".
- Isan (Northeastern Thai), the language of the Isan region of Thailand, a collective term for the various Lao dialects spoken in Thailand that show some Siamese Thai influences, which is written with the Thai script. It is spoken by about over 20 million people. Thais from both inside and outside the Isan region often simply call this variant "Lao" when speaking informally.
- 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). Shares strong similarities with Lao to the point that in the past the Siamese Thais referred to it as Lao.
- Southern Thai (Thai Tai, Pak Tai, or Dambro), spoken by about 4.5 million (2006)
- Phu Thai, spoken by about half a million around Nakhon Phanom Province, and 300,000 more in Laos and Vietnam (2006).
- Phuan, spoken by 200,000 in central Thailand and Isan, and 100,000 more in northern Laos (2006).
- Shan (Thai Luang, Tai Long, Thai Yai), spoken by about 100,000 in north-west Thailand along the border with the Shan States of Burma, and by 3.2 million in Burma (2006).
- Lü (Tai Lue, Dai), spoken by about 80,000 (2001) in northern Thailand, and 600,000 more in China, Burma, and Laos (1981–2000).
- Nyaw language, spoken by 50,000 in Nakhon Phanom Province, Sakhon Nakhon Province, Udon Thani Province of Northeast Thailand (1990).
- Song, spoken by about 30,000 in central and northern Thailand (2000).
Siamese Thai is composed of several distinct registers, forms for different social contexts:
- Street or common Thai (ภาษาพูด, spoken Thai): informal, without polite terms of address, as used between close relatives and friends.
- Elegant or formal 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 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 the national curriculum.
Many scholars believe that the Thai script is derived from the Khmer script, 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 the Khmer script. 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. 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 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:
- 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 final onset consonant 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.
There is no universally applied method for transcribing Thai into the Latin alphabet. For example, the name of the main airport is transcribed variously as Suvarnabhumi, Suwannaphum, or Suwunnapoom. Guide books, text books and dictionaries may each follow different systems. For this reason, most language courses recommend that learners master the Thai script.
Official standards are the International Organization for Standardization. The RTGS 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. 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 2003 (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 seems not to appear in many other contexts, such as textbooks and other instructional media. This may be because the particular problems of writing Thai for foreigners, including silent letters and placement of vowel markers, decrease the usefulness of literal transliteration.
Thai distinguishes three voice-onset times among plosive and affricate consonants:
Where English makes a distinction between voiced /b/ and aspirated /pʰ/, Thai distinguishes a third sound that is neither voiced nor aspirated, which occurs in English only as an allophone of /pʰ/, for example after an /s/ as in the sound of the p in "spin". There is similarly an alveolar /t/, /tʰ/, /d/ triplet in Thai. In the velar series there is a /k/, /kʰ/ pair and in the postalveolar series a /t͡ɕ/, /t͡ɕʰ/ pair, but the language lacks the corresponding voiced sounds /ɡ/ and /dʑ/. (In loanwords from English, English /ɡ/ and /d͡ʒ/ are borrowed as the tenuis stops /k/ and /t͡ɕ/.)
In each cell below, the first line indicates (IPA), the second indicates the Thai characters in initial position (several letters appearing in the same box have identical pronunciation).
- * ฃ and ฅ are no longer used. Thus, modern Thai is said to have 42 consonant letters.
- ** Initial อ is silent and therefore considered as glottal plosive.
Although the overall 44 Thai consonant letters provide 21 sounds in case of initials, the case for finals is different. For finals, only eight sounds, as well as no sound, called mātrā (มาตรา) are used. To demonstrate, at the end of a syllable, บ (/b/) and ด (/d/) are devoiced, becoming pronounced as /p/ and /t/ respectively. Additionally, all plosive sounds are unreleased. Hence, final /p/, /t/, and /k/ sounds are pronounced as [p̚], [t̚], and [k̚] respectively.
Of the consonant letters, excluding the disused ฃ and ฅ, six (ฉ ผ ฝ ห อ ฮ) cannot be used as a final and the other 36 are grouped as following.
- * The glottal plosive appears at the end when no final follows a short vowel
In Thai, each syllable in a word is considered separate from the others, so combinations of consonants from adjacent syllables are never recognised as a cluster. Thai has phonotactical constraints that define permissible syllable structure, consonant clusters, and vowel sequences. Original Thai vocabulary introduces only 11 combined consonantal patterns:
- /kr/ (กร), /kl/ (กล), /kw/ (กว)
- /kʰr/ (ขร,คร), /kʰl/ (ขล,คล), /kʰw/ (ขว,คว)
- /pr/ (ปร), /pl/ (ปล)
- /pʰr/ (พร), /pʰl/ (ผล,พล)
- /tr/ (ตร)
The number of clusters increases when a few more combinations are presented in loanwords such as /tʰr/ (ทร) in อินทรา (/intʰraː/, from Sanskrit indrā) or /fr/ (ฟร) in ฟรี (/friː/, from English free); however, it can be observed that Thai language supports only those in initial position, with either /r/, /l/, or /w/ as the second consonant sound and not more than two sounds at a time.
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 , 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:
|–า||/aː/||ฝาน||/fǎːn/||'to slice'||–ะ||/a/||ฝัน||/fǎn/||'to dream'|
|เ–||/eː/||เอน||/ʔēːn/||'to recline'||เ–ะ||/e/||เอ็น||/ʔēn/||'tendon, ligament'|
|แ–||/ɛː/||แพ้||/pʰɛ́ː/||'to be defeated'||แ–ะ||/ɛ/||แพะ||/pʰɛ́ʔ/||'goat'|
|–ื-||/ɯː/||คลื่น||/kʰlɯ̂ːn/||'wave'||–ึ||/ɯ/||ขึ้น||/kʰɯ̂n/||'to go up'|
|โ–||/oː/||โค่น||/kʰôːn/||'to fell'||โ–ะ||/o/||ข้น||/kʰôn/||'thick (soup)'|
The basic vowels can be combined into diphthongs. Tingsabadh & Abramson (1993) analyze those ending in high vocoids as underlyingly /Vj/ and /Vw/. For purposes of determining tone, those marked with an asterisk are sometimes classified as long:
|–าย||/aːj/||ไ–*, ใ–*, ไ–ย, -ัย||/aj/|
Additionally, there are three triphthongs, all of which are long:
For a guide to written vowels, see the Thai alphabet page.
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.
The full complement of tones exists only in so-called "live syllables", those that end in a long vowel or a sonorant (/m/, /n/, /ŋ/, /j/, /w/).
For "dead syllables", those that end in a plosive (/p/, /t/, /k/) or in a short vowel, only three tonal distinctions are possible: low, high, and falling. Because syllables analyzed as ending in a short vowel may have a final glottal stop (especially in slower speech), all "dead syllables" are phonetically checked, and have the reduced tonal inventory characteristic of checked syllables. In native words that have been used for a very long time, only a two-way tonal distinction occurs: falling vs. low for syllables containing a long vowel, and high vs. low for syllables containing a short vowel (i.e. ending either in a short vowel + plosive, or in a short vowel alone).
|low||เอก||หน่า||/nàː/||[naː˨˩] or [naː˩]||(a nickname)|
|high||ตรี||น้า||/náː/||[naː˦˥] or [naː˥]||maternal aunt or uncle younger than one's mother|
|rising||จัตวา||หนา||/nǎː/||[naː˩˩˦] or [naː˩˦]||thick|
|low (short vowel)||เอก||หมัก||/màk/||[mak̚˨˩]||marinate|
|low (long vowel)||เอก||หมาก||/màːk/||[maːk̚˨˩]||areca nut, areca palm, betel, fruit|
|high||ตรี||มัก||/mák/||[mak̚˦˥]||habitually, likely to|
|falling||โท||มาก||/mâːk/||[maːk̚˥˩]||a lot, abundance, many|
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.
- คนอ้วน (khon uan, [kʰon ʔûan ]) a fat person
- คนที่อ้วนเร็ว (khon thi uan reo, [khon tʰîː ʔûan rew]) a person who became fat quickly
- เขาอ้วนกว่าฉัน (khao uan kwa chan, [kʰǎw ʔûan kwàː tɕ͡ʰǎn]) S/he is fatter than me.
- เขาอ้วนที่สุด (khao uan thi sut, [kʰǎw ʔûan tʰîːsùt]) 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, [tɕ͡ʰǎn hǐw]) I am hungry.
- ฉันจะหิว (chan cha hiu, [tɕ͡ʰǎn tɕ͡àʔ hǐw]) I will be hungry.
- ฉันกำลังหิว (chan kamlang hiu, [tɕ͡ʰǎn kamlaŋ hǐw]) I am hungry right now.
- ฉันหิวแล้ว (chan hiu laeo, [tɕ͡ʰǎn hǐw lɛ́ːw]) I am already hungry.
- Remark ฉันหิวแล้ว mostly means "I am hungry right now" because normally, แล้ว ([lɛ́ːw]) is a past-tense marker, but แล้ว has many other uses as well. For example, in the sentence, แล้วเธอจะไปไหน ([lɛ́ːw tʰɤː tɕ͡àʔ paj nǎj]): So where are you going?, แล้ว ([lɛ́ːw]) is used as a discourse particle.
- ฉันตีเขา (chan ti khao, [t͡ɕʰǎn tiː kʰǎw]), I hit him.
- เขาตีฉัน (khao ti chan, [kʰǎw tiː t͡ɕʰǎn]), He hit me.
The passive voice is indicated by the insertion of ถูก (thuk, [tʰùːk]) before the verb. For example:
- เขาถูกตี (khao thuk ti, [kʰǎw tʰùːk tiː]), 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, [dâj], can) is used. For example:
- เขาจะได้ไปเที่ยวเมืองลาว (khao cha dai pai thiao mueang lao, [kʰǎw t͡ɕaʔ dâj paj tʰîow mɯːaŋ laːw]), He gets to visit Laos.
Note, dai ([dâj] and [dâːj]), though both spelled ได้, convey two separate meanings. The short vowel dai ([dâj]) conveys an opportunity has arisen and is placed before the verb. The long vowel dai ([dâːj]) 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, [kʰǎw tiː dâːj]), He is/was allowed to hit or He is/was able to hit
Negation is indicated by placing ไม่ (mai,[mâj] not) before the verb.
- เขาไม่ตี, (khao mai ti) He is not hitting. or He not hit.
Present can be indicated by กำลัง (kamlang, [kamlaŋ], currently) before the verb for ongoing action (like English -ing form), by อยู่ (yu, [jùː]) after the verb, or by both. For example:
- เขากำลังวิ่ง (khao kamlang wing, [kʰǎw kamlaŋ wîŋ]), or
- เขาวิ่งอยู่ (khao wing yu, [kʰǎw wîŋ jùː]), or
- เขากำลังวิ่งอยู่ (khao kamlang wing yu, [kʰǎw kamlaŋ wîŋ jùː]), He is running.
Future can be indicated by จะ (cha, [t͡ɕaʔ], will) before the verb or by a time expression indicating the future. For example:
- เขาจะวิ่ง (khao cha wing, [kʰǎw t͡ɕaʔ wîŋ]), He will run or He is going to run.
Past can be indicated by ได้ (dai, [dâːj]) before the verb or by a time expression indicating the past. However, แล้ว (laeo, :[lɛ́ːw], already) is 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. For example:
- เขาได้กิน (khao dai kin, [kʰǎw dâːj kin]), He ate.
- เขากินแล้ว (khao kin laeo, [kʰǎw kin lɛ́ːw], He has eaten.
- เขาได้กินแล้ว (khao dai kin laeo, [kʰǎw dâːj kin lɛ́ːw]), He's already eaten.
Tense markers are not required.
- ฉันกินที่นั่น (chan kin thinan, [t͡ɕʰǎn kin tʰìːnàn]), I eat there.
- ฉันกินที่นั่นเมื่อวาน (chan kin thinan mueawan), I ate there yesterday.
- ฉันกินที่นั่นพรุ่งนี้ (chan kin thinan phrungni), I'll eat there tomorrow.
Thai exhibits serial verb constructions, where verbs are strung together. Some word combinations are common and may be considered set phrases.
- เขาไปกินข้าว (khao pai kin khao, [kʰǎw paj kin kʰâːw]) He went out to eat, literally He go eat rice
- ฉันฟังไม่เข้าใจ (chan fang mai khao chai, [tɕ͡ʰǎn faŋ mâj kʰâw tɕ͡aj]) I don't understand what was said, literally I listen not understand
- เข้ามา (khao ma, [kʰâw maː]) Come in, literally enter come
- ออกไป! (ok pai, [ʔɔ̀ːk paj]) Leave! or Get out!, literally exit go
Nouns are neither singular nor plural. Some specific nouns are reduplicated to form collectives: เด็ก (dek, child) is often repeated as เด็ก ๆ (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, [pʰûak pʰǒm], we, masculine; พวกเรา phuak rao, [pʰûak raw], 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, with nicknames used where English would use a pronoun. See informal and formal names for more details. Pronouns, when used, are ranked in honorific registers, and may also make a T–V distinction in relation to kinship and social status. Specialised pronouns are used for those with royal and noble titles, and for clergy. The following are appropriate for conversational use:
|ผม||phom||[pʰǒm]||I/me (masculine; formal)|
|ดิฉัน||dichan||[dìʔt͡ɕʰán])||I/me (feminine; formal)|
|ฉัน||chan||[t͡ɕʰǎn]||I/me (mainly used by women; informal) Commonly pronounced as [t͡ɕʰán]|
|เรา||rao||[raw]||we/us, I/me (casual), you (sometimes used but only when older person speaks to younger person)|
|ท่าน||than||[tʰân]||you (highly honorific)|
|เธอ||thoe||[tʰɤː]||you (informal), she/her (informal)|
|พี่||phi||[pʰîː]||older brother, sister (also used for older acquaintances)|
|น้อง||nong||[nɔːŋ]||younger brother, sister (also used for younger acquaintances)|
|มัน||man||[man]||it, he/she (sometimes casual or offensive if used to refer to a person)|
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 also 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). Plural pronouns can be easily constructed by adding the word พวก (puak) in front of a singular pronoun as in พวกเขา (puak khao) meaning they or พวกเธอ (puak thoe) meaning the plural sense of you. The only exception to this is เรา (rao), which can be used as singular (informal) or plural, but can also be used in the form of พวกเรา (puak rao), which is only plural.
Thai has many more pronouns than those listed above. Their usage is full of nuances. For example:
- "ผม เรา ฉัน ดิฉัน หนู กู ข้า กระผม ข้าพเจ้า กระหม่อม อาตมา กัน ข้าน้อย ข้าพระพุทธเจ้า อั๊ว เขา" all translate to "I", but each expresses a different gender, age, politeness, status, or relationship between 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 is 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.
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) when the speaker is male, and ค่ะ (kha, [kʰâ], with a falling tone) when the speaker is female; 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:
|จ๊ะ||cha/ja||[t͡ɕáʔ]||indicating a request|
|จ้ะ, จ้า or จ๋า||cha/ja||[t͡ɕâː]||indicating emphasis|
|ละ or ล่ะ||la||[láʔ]||indicating emphasis|
|สิ||si||[sìʔ]||indicating emphasis or an imperative|
|นะ||na||[náʔ]||softening; indicating a request|
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 copious borrowed words from Middle Chinese.Later most vocabulary was 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, especially for scientific and technical vocabulary. Many Teochew Chinese words are also used, some replacing existing Thai words (for example, the names of basic numbers; see also Sino-Xenic).
Middle Chinese and/or
Pali and/or Sanskrit
|รับประทาน||/ráp.pra.tʰāːn/||formal, polite||Often shortened to ทาน /tʰāːn/.|
Thai has undergone various historical sound changes. Some of the most significant changes, at least in terms of consonants and tones, occurred between Old Thai spoken when the language was first written and Thai of present, reflected in the orthography.
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 /p/, /t/, /k/ or the glottal stop which 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 (/p pʰ b ʔb/) and dentals (/t tʰ d ʔd/); the three-way distinction among velars (/k kʰ ɡ/) and palatals (/tɕ tɕʰ dʐ/), 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 AD, possibly occurring at different times in different parts of the Thai-speaking area. All voiced–voiceless pairs of consonants lost the voicing distinction:
- Plain voiced stops (/b d ɡ dʐ/) became voiceless aspirated stops (/pʰ tʰ kʰ tɕʰ/).
- Voiced fricatives became voiceless.
- Voiceless sonorants became voiced.
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 /p t k tɕ ʔb ʔd/) 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 Thai — precisely 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. Note also that 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 /x ɣ/ as distinct phonemes. These were represented by the now-obsolete letters ฃ kho khuat and ฅ kho khon, respectively. During the Old Thai period, these sounds merged into the corresponding stops /kʰ ɡ/, and as a result the use of these letters became unstable.
At some point in the history of Thai, a palatal nasal phoneme /ɲ/ also existed, inherited from Proto-Tai. A letter ญ yo ying also exists, which is used to represent a palatal nasal in words borrowed from Sanskrit and Pali, and is currently pronounced /j/ at the beginning of a syllable but /n/ at the end of a syllable. Most native Thai words that are reconstructed as beginning with /ɲ/ are also pronounced /j/ in modern Thai, but generally spelled with ย yo yak, which consistently represents /j/. This suggests that /ɲ/ > /j/ in native words occurred in the pre-literary period. It is unclear whether Sanskrit and Pali words beginning with /ɲ/ were borrowed directly with a /j/, or whether a /ɲ/ was re-introduced, followed by a second change /ɲ/ > /j/.
Proto-Tai also had a glottalized palatal sound, reconstructed as /ʔj/ in Li Fang-Kuei (1977). Corresponding Thai words are generally spelled หย, which implies an Old Thai pronunciation of /hj/ (or /j̊/), but a few such words are spelled อย, which implies a pronunciation of /ʔj/ 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 short–long pair (/a aː/), and in general it is difficult or impossible to find minimal short–long pairs in Thai that involve vowels other than /a/ and where both members have frequent correspondences throughout the Tai languages. More specifically, he notes the following facts about Thai:
- In open syllables, only long vowels occur. (This assumes that all apparent cases of short open syllables are better described as ending in a glottal stop. This makes sense from the lack of tonal distinctions in such syllables, and the glottal stop is also reconstructible across the Tai languages.)
- In closed syllables, the long high vowels /iː ɯː uː/ are rare, and cases that do exist typically have diphthongs in other Tai languages.
- In closed syllables, both short and long mid /e eː o oː/ and low /ɛ ɛː ɔ ɔː/ do occur. However, generally, only words with short /e o/ and long /ɛː ɔː/ are reconstructible back to Proto-Tai.
- Both of the mid back unrounded vowels /ɤ ɤː/ are rare, and words with such sounds generally cannot be reconstructed back to Proto-Tai.
Furthermore, the vowel that corresponds to short Thai /a/ has a different and often higher quality in many of the Tai languages compared with the vowel corresponding to Thai /aː/.
This leads Li to posit the following:
- Proto-Tai had a system of nine pure vowels with no length distinction, and possessing approximately the same qualities as in modern Thai: high /i ɯ u/, mid /e ɤ o/, low /ɛ a ɔ/.
- All Proto-Tai vowels were lengthened in open syllables, and low vowels were also lengthened in closed syllables.
- Modern Thai largely preserved the original lengths and qualities, but lowered /ɤ/ to /a/, which became short /a/ in closed syllables and created a phonemic length distinction /a aː/. Eventually, length in all other vowels became phonemic as well and a new /ɤ/ (both short and long) was introduced, through a combination of borrowing and sound change. Li believes that the development of long /iː ɯː uː/ from diphthongs, and the lowering of /ɤ/ to /a/ to create a length distinction /a aː/, had occurred by the time of Proto-Southwestern-Tai, but the other missing modern Thai vowels had not yet developed.
Note that 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 /ǝ/ (which he describes as /ɤ/), occurring only before final velar /k ŋ/. He also seems to believe that the Proto-Southwestern-Tai vowel length distinctions can be reconstructed back to similar distinctions in Proto-Tai.
- Thai at Ethnologue (17th ed., 2013)
- Nordhoff, Sebastian; Hammarström, Harald; Forkel, Robert; Haspelmath, Martin, eds. (2013). "Thai". Glottolog 2.2. Leipzig: Max Planck Institute for Evolutionary Anthropology.
- In Thai: ภาษาไทย Phasa Thai ( )
- Although "Thai" has become more common, the older term "Siamese" is still used by linguists, especially when disambiguating from other Tai languages (Diller 2008:6). "Proto-Thai", for example, is the ancestor of all of Southwestern Tai, not just of Siamese (Rischel 1998).
- Not to be confused with Central Tai
- "Ausbau and Abstand languages". Ccat.sas.upenn.edu. 1995-01-20. Retrieved 2012-07-08.
Andrew Simpson (2007). Language and national identity in Asia. Oxford University Press.
Standard Thai is a form of Central Thai based on the variety of Thai spoken earlier by the elite of the court, and now by the educated middle and upper classes of Bangkok. It ... was standardized in grammar books in the nineteenth century, and spread dramatically from the 1930s onwards, when public education became much more widespread
Peansiri Vongvipanond (Summer 1994). "Linguistic Perspectives of Thai Culture". paper presented to a workshop of teachers of social science. University of New Orleans. p. 2. Retrieved 26 April 2011.
The dialect one hears on radio and television is the Bangkok dialect, considered the standard dialect.
- Antonio L. Rappa; Lionel Wee (2006), Language Policy and Modernity in Southeast Asia: Malaysia, the Philippines, Singapore, and Thailand, Springer, pp. 114–115
- Royal Thai General System of Transcription, published by the Thai Royal Institute only in Thai
- ISO Standard.
- Tingsabadh & Abramson (1993:25)
- Frankfurter, Oscar. Elements of Siamese grammar with appendices. American Presbyterian mission press, 1900  (Full text available on Google Books)
- Martin Haspelmath, Uri Tadmor Loanwords in the World's Languages: A Comparative Handbook 2009 -- Page 611 "Thai is of special interest to lexical borrowing for various reasons. The copious borrowing of basic vocabulary from Middle Chinese and later from Khmer indicates that, given the right sociolinguistic context, such vocabulary is not at all immune ..."
- Harald Haarmann Language in Ethnicity: A View of Basic Ecological Relations 1986- Page 165 "In Thailand, for instance, where the Chinese influence was strong until the Middle Ages, Chinese characters were abandoned in written Thai in the course of the thirteenth century."
- Paul A. Leppert Doing Business With Thailand -1992 Page 13 "At an early time the Thais used Chinese characters. But, under the influence of Indian traders and monks, they soon dropped Chinese characters in favor of Sanskrit and Pali scripts."
- The glottalized stops /ʔb ʔd/ were unaffected, as they were treated in every respect like voiceless unaspirated stops due to the initial glottal stop. These stops are often described in the modern language as phonemically plain stops /b d/, but the glottalization is still commonly heard.
- Modern Lao and northern Thai dialects are often described as having six tones, but these are not necessarily due to preservation of the original six tones resulting from the tone split. For example, in standard Lao, both the high and low variants of Old Thai tone 2 merged; however, the mid-class variant of tone 1 became pronounced differently from either the high-class or low-class variants, and all three eventually became phonemic due to further changes, e.g. /kr/ > /kʰ/. For similar reasons, Lao has developed more than two tonal distinctions in "dead" syllables.
- อภิลักษณ์ ธรรมทวีธิกุล และ กัลยารัตน์ ฐิติกานต์นารา. 2549.“การเน้นพยางค์กับทำนองเสียงภาษาไทย” (Stress and Intonation in Thai ) วารสารภาษาและภาษาศาสตร์ ปีที่ 24 ฉบับที่ 2 (มกราคม – มิถุนายน 2549) หน้า 59-76
- สัทวิทยา : การวิเคราะห์ระบบเสียงในภาษา. 2547. กรุงเทพฯ : สำนักพิมพ์มหาวิทยาลัยเกษตรศาสตร์
- Diller, Anthony van Nostrand. 2008. The Tai–Kadai Languages.
- Gandour, Jack, Tumtavitikul, Apiluck and Satthamnuwong, Nakarin. 1999. “Effects of Speaking Rate on the Thai Tones.” Phonetica 56, pp. 123–134.
- Li, Fang-Kuei. A handbook of comparative Tai. Honolulu: University Press of Hawaii, 1977. Print.
- Rischel, Jørgen. 1998. 'Structural and Functional Aspects of Tone Split in Thai'. In Sound structure in language, 2009.
- Tumtavitikul, Apiluck, 1998. “The Metrical Structure of Thai in a Non-Linear Perspective”. Papers presentd to the Fourth Annual Meeting of the Southeast Asian Linguistics Society 1994, pp. 53–71. Udom Warotamasikkhadit and Thanyarat Panakul, eds. Temple,Arizona:Program for Southeast Asian Studies, Arizona State University.
- Apiluck Tumtavitikul. 1997. “The Reflection on the X’ category in Thai”. Mon–Khmer Studies XXVII, pp. 307–316.
- อภิลักษณ์ ธรรมทวีธิกุล. 2539. “ข้อคิดเกี่ยวกับหน่วยวากยสัมพันธ์ในภาษาไทย” วารสารมนุษยศาสตร์วิชาการ. 4.57-66.
- Tumtavitikul, Appi. 1995. “Tonal Movements in Thai”. The Proceedings of the XIIIth International Congress of Phonetic Sciences, Vol. I, pp. 188–121. Stockholm: Royal Institute of Technology and Stockholm University.
- Tumtavitikul, Apiluck. 1994. “Thai Contour Tones”.Current Issues in Sino-Tibetan Linguistics, pp. 869–875. Hajime Kitamura et al., eds, Ozaka: The Organization Committee of the 26th Sino-Tibetan Languages and Linguistics,National Museum of Ethnology.
- Tumtavitikul, Apiluck. 1993. “FO – Induced VOT Variants in Thai”. Journal of Languages and Linguistics, 12.1.34 – 56.
- Tumtavitikul, Apiluck. 1993. “Perhaps, the Tones are in the Consonants?” Mon–Khmer Studies XXIII, pp. 11–41.
- Higbie, James and Thinsan, Snea. Thai Reference Grammar: The Structure of Spoken Thai. Bangkok: Orchid Press, 2003. ISBN 974-8304-96-5.
- Nacaskul, Karnchana, Ph.D. (ศาสตราจารย์กิตติคุณ ดร.กาญจนา นาคสกุล) Thai Phonology, 4th printing. (ระบบเสียงภาษาไทย, พิมพ์ครั้งที่ 4) Bangkok: Chulalongkorn Press, 1998. ISBN 978-974-639-375-1.
- Nanthana Ronnakiat, Ph.D. (ดร.นันทนา รณเกียรติ) 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 (2002). Thai: An Essential Grammar, first edition. London: Routledge.
- Smyth, David (2014). Thai: An Essential Grammar, second edition. London: Routledge.
- Tingsabadh, M.R. Kalaya; Abramson, Arthur (1993), "Thai", Journal of the International Phonetic Association 23 (1): 24–28,
- IPA and SAMPA for Thai
- Structure of Thai Language (TH101) PDF version of university text book
Glossaries and word lists
- Thai phrasebook from Wikivoyage
- Thai Swadesh list of basic vocabulary words (from Wiktionary's Swadesh-list appendix)
- English-Thai dictionary, NECTEC English<–>Thai dictionary; free download with sound files.
- English–Thai Dictionary: English–Thai bilingual online dictionary
- The Royal Institute Dictionary, official standard Thai–Thai dictionary
- Longdo Thai Dictionary LongdoDict
- Thai-English dictionary
- Thai2english.com: LEXiTRON-based Thai–English dictionary
- Daoulagad Thai: mobile OCR Thai–English dictionary
- Thai dictionaries for Stardict/GoldenDict - Thai - English (French, German, Russian and others) dictionaries in Stardict and GoldenDict formats
- Volubilis Dictionary VOLUBILIS (Romanized Thai - Thai - English - French) : free databases (ods/xlsx) and dictionaries (PDF)
- ThaiLearner ★★★★★ Free Android software to learn Thai language
- thai-language.com English speakers' online resource for the Thai language
- Say Hello in the Thai Language
- Thai Language Wiki (Online lectures)
- Spoken Thai (30 exercises with audio)
- Thai books+Audio, a lot of books in Thai with audio.
- USA Foreign Service Institute (FSI) Thai basic course
- Thai Keyboard Virtual Thai Keyboard