Thai alphabet

History

The Thai alphabet is derived from the Old Khmer script (Thai: อักษรขอม, akson khom), which is a southern Brahmic style of writing derived from the south Indian Pallava alphabet (Thai: ปัลลวะ).

Thai is considered to be the first script in the world which invented tone markers to indicate distinctive tones, which are lacking in the Mon-Khmer and Indo-Aryan languages from which its script is derived. Although Chinese and other Sino-Tibetan languages have distinctive tones in their phonological system, no tone marker is found in their orthographies. Thus, tone markers are an innovation in the Thai language that later influenced other related Tai languages and some Tibeto-Burman languages on the Southeast Asian mainland.

Thai tradition attributes the creation of the script to King Ramkhamhaeng the Great (Thai: พ่อขุนรามคำแหงมหาราช) in 1283, though this has been challenged.

Orthography

There is a fairly complex relationship between spelling and sound. There are various issues:

1. For many consonant sounds, there are two different letters that both represent the same sound, but which cause a different tone to be associated. This stems from a major change (a tone split) that occurred historically in the phonology of the Thai language. At the time the Thai script was created, the language had three tones and a full set of contrasts between voiced and unvoiced consonants at the beginning of a syllable (e.g. b d g l m n vs. p t k hl hm hn). At a later time, the voicing distinction disappeared, but in the process, each of the three original tones split in two, with an originally voiced consonant (the modern "low" consonant signs) producing a lower-variant tone, and an originally unvoiced consonant (the modern "mid" and "high" consonant signs) producing a higher-variant tone.
2. Thai borrowed a large number of words from Sanskrit and Pali, and the Thai alphabet was created so that the original spelling of these words could be preserved as much as possible. This means that the Thai alphabet has a number of "duplicate" letters that represent separate sounds in Sanskrit and Pali (e.g. the breathy voiced sounds bh, dh, ḍh, jh, gh and the retroflex sounds ṭ ṭh ḍ ḍh ṇ) but which never represented distinct sounds in the Thai language. These are mostly or exclusively used in Sanskrit and Pali borrowings.
3. The desire to preserve original Sanskrit and Pali spellings also produces a particularly large number of duplicate ways of spelling sounds at the end of a syllable (where Thai is strictly limited in the sounds that can occur but Sanskrit allowed all possibilities, especially once former final /a/ was deleted), as well as a number of silent letters. Moreover, many consonants from Sanskrit and Pali loanwords are generally silent. The spelling of the words resembles Sanskrit or Pali orthography:
4. Thai สามารถ (spelled sǎamaarth but pronounced sa-mat [sǎːmâːt] with a silent r and a plain t that is represented using an aspirated consonant) "to be able" (Sanskrit समर्थ samartha)
5. Thai จันทร์ (spelled chanthr but pronounced chan [tɕan] because the th and the r are silent) "moon" (Sanskrit चन्द्र chandra)

Thai letters do not have small and capital forms like the Roman alphabet. Spaces between words are not used, except in certain linguistically motivated cases.

Punctuation

Minor pauses in sentences may be marked by a comma (Thai: จุลภาค or ลูกน้ำ, chunlaphak or luk nam), and major pauses by a period (Thai: มหัพภาค or จุด, mahap phak or chut), but most often are marked by a blank space (Thai: วรรค, wak). A bird's eye ๏ (Thai: ตาไก่, ta kai, officially called ฟองมัน, fong man) formerly indicated paragraphs, but is now obsolete.

A kho mut ๛ (Thai: โคมูตร) can be used to mark the end of a chapter or document.

Thai writing also uses quotation marks (Thai: อัญประกาศ, anyaprakat) and parentheses (round brackets) (Thai: วงเล็บ, wong lep or Thai: นขลิขิต, nakha likhit), but not square brackets or braces.

Consonants

There are 44 consonant letters representing 21 distinct consonant sounds. Duplicate consonants either correspond to sounds that existed in Old Thai at the time the alphabet was created but no longer exist (in particular, voiced obstruents such as b d g v z), or different Sanskrit and Pali consonants pronounced identically in Thai. There are in addition four consonant-vowel combination characters not included in the tally of 44.

Consonants are divided into three classes — in alphabetic order these are middle (กลาง, klang,) high (สูง, sung,) and low (ต่ำ, tam) class — as shown in the table below. These class designations reflect phonetic qualities of the sounds to which the letters originally corresponded in Old Thai. In particular, "middle" sounds were voiceless unaspirated stops; "high" sounds, voiceless aspirated stops or voiceless fricatives; "low" sounds, voiced. Subsequent sound changes have obscured the phonetic nature of these classes. Today, the class of a consonant without a tone mark, along with the short or long length of the accompanying vowel, determine the base accent (พื้นเสียง, pheun siang.) Middle class consonants with a long vowel spell an additional four tones with one of four tone marks over the controlling consonant: mai ek, mai tho, mai tri, and mai chattawa. High and low class consonants are limited to mai ek and mai tho, as shown in the Tone table. Differing interpretations of the two marks or their absence allow low class consonants to spell tones not allowed for the corresponding high class consonant. In the case of digraphs where a low class follows a higher class consonant, the higher class rules apply, but the marker, if used, goes over the low class one; accordingly, ห นำ ho nam and อ นำ o nam may be considered to be digraphs as such, as explained below the Tone table.

Notes

To aid learning, each consonant is traditionally associated with an acrophonic Thai word that either starts with the same sound, or features it prominently. For example, the name of the letter ข is kho khai (ข ไข่), in which kho is the sound it represents, and khai (ไข่) is a word which starts with the same sound and means "egg".

Two of the consonants, ฃ (kho khuat) and ฅ (kho khon), are no longer used in written Thai, but still appear on many keyboards and in character sets. When the first Thai typewriter was developed by Edwin Hunter McFarland in 1892, there was simply no space for all characters, thus two had to be left out. Also, neither of these two letters correspond to a Sanskrit or Pali letter, and each of them, being a modified form of the letter that precedes it (compare ข and ค), has the same pronunciation and the same consonant class as the preceding letter (somewhat like the European long s). This makes them redundant. Set in 1890s Siam, a 2006 film titled in Thai: ฅนไฟบิน Flying Fire Person (in English: Dynamite Warrior), uses ฅ kho khon to spell ฅน Person. Compare entry for ฅ in table below, where person is spelled คน.

Equivalents for romanisation are shown in the table below. Many consonants are pronounced differently at the beginning and at the end of a syllable. The entries in columns initial and final indicate the pronunciation for that consonant in the corresponding positions in a syllable. Where the entry is '-', the consonant may not be used to close a syllable. Where a combination of consonants ends a written syllable, only the first is pronounced; possible closing consonant sounds are limited to 'k', 'm', 'n', 'ng', 'p' and 't'.

Although official standards for romanisation are the Royal Thai General System of Transcription (RTGS) defined by the Royal Thai Institute, and the almost identical ISO 11940-2 defined by the International Organization for Standardization, many publications use different romanisation systems. In daily practice, a bewildering variety of romanisations are used, making it difficult to know how to pronounce a word, or to judge if two words (e.g. on a map and a street sign) are actually the same. For more precise information, an equivalent from the International Phonetic Alphabet (IPA) is given as well.

Phonetic

The consonants can be organised by place and manner of articulation according to principles of the International Phonetic Association. 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 /pʰ/, 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 International Phonetic Alphabet (IPA), the second indicates the Thai characters in initial position (several letters appearing in the same box have identical pronunciation). Note how the conventional alphabetic order shown in the table above follows roughly the table below, reading the coloured blocks from right to left and top to bottom.

Pronunciation of Thai characters in initial position

Although the overall 44 Thai consonants provide 21 sounds in case of initials, the case for finals is different. Note how the consonant sounds in the table for initials collapse in the table for final sounds. At the end of a syllable, all plosives are unvoiced, unaspirated, and have no audible release. Initial affricates and fricatives become final plosives. The initial trill (ร), approximant (ญ), and lateral approximants (ล,ฬ) are realized as a final nasal /n/.

Only 8 ending sounds, as well as no ending sound, are available in Thai pronunciation. Among these consonants, excluding the disused ฃ and ฅ, six (ฉ ผ ฝ ห อ ฮ) cannot be used as a final. The remaining 36 are grouped as following.

Pronunciation of Thai characters in final position

Vowels

Thai vowel sounds and diphthongs are written using a mixture of vowel symbols on a consonant base. Each vowel is shown in its correct position relative to a base consonant and sometimes a final consonant as well. Note that vowels can go above, below, left of or right of the consonant, or combinations of these places. If a vowel has parts before and after the initial consonant, and the syllable starts with a consonant cluster, the split will go around the whole cluster.

Twenty-one vowel symbol elements are traditionally named, which may appear alone or in combination to form compound symbols.

The inherent vowels are /a/ in open syllables (CV) and /o/ in closed syllables (CVC). For example, ถนน transcribes /tʰànǒn/ "road". There are a few exceptions in Pali loanwords, where the inherent vowel of an open syllable is /o/. The circumfix vowels, such as เ–าะ /ɔʔ/, encompass a preceding consonant with an inherent vowel. For example, /pʰɔʔ/ is written เพาะ, and /tɕʰapʰɔʔ/ "only" is written เฉพาะ.

The characters ฤ ฤๅ (plus ฦ ฦๅ, which are obsolete) are usually considered as vowels, the first being a short vowel sound, and the latter, long. As alphabetical entries, ฤ ฤๅ follow ร, and themselves can be read as a combination of consonant and vowel, equivalent to รึ (short), and รือ (long) (and the obsolete pair as ลึ, ลือ), respectively. Moreover, ฤ can act as ริ as an integral part in many words mostly borrowed from Sanskrit such as กฤษณะ (kritsana, not kruetsana), ฤทธิ์ (rit, not ruet), and กฤษดา (kritsada, not kruetsada), for example. It is also used to spell อังกฤษ angkrit England/English.

The pronunciation below is indicated by the International Phonetic Alphabet and the Romanisation according to the Royal Thai Institute as well as several variant Romanisations often encountered. A very approximate equivalent is given for various regions of English speakers and surrounding areas. Dotted circles represent the positions of consonants or consonant clusters. The first one represents the initial consonant and the latter (if it exists) represents the final.

Ro han (ร หัน) is not usually considered a vowel and is not included in the following table. It represents the sara a /a/ vowel in certain Sanskrit loanwords and appears as ◌รร◌. When used without a final consonant (◌รร), /n/ is implied as the final consonant, giving [an].

^ Only with ร (ro ruea) as final consonant, appearing as ◌ร [ɔːn].

^ Only with the word ก็ [kɔ̂ː].

^ Used only in certain words.

^ Mai malai (ไ◌) is used for the [ai] vowel in most words, while mai muan (ใ◌) is only used in twenty specific words.

^ ไ◌ย is found in ไทย Thai and in Pali loanwords which contain -eyya. The ย is redundant, but may be pronounced in a compound word when joined by samāsa.

^ Traditionally, these sets of diphthongs and triphthongs are regarded as combinations of regular vowels or diphthongs with wo waen (ว, /w/) or yo yak (ย, /j/) as the final consonant, and are not counted among the thirty-two vowels.

^ Extra vowels are not distinct vowel sounds, but are symbols that represent certain vowel-consonant combinations. They are traditionally regarded as vowels, although some sources do not.

^ Sara ai (ใ◌ and ไ◌)and sara ao (เ◌า) are also considered extra vowels.

Tone

Thai is a tonal language, and the script gives full information on the tones. Tones are realised in the vowels, but indicated in the script by a combination of the class of the initial consonant (high, mid or low), vowel length (long or short), closing consonant (plosive or sonorant, i.e., dead or live) and, if present, one of four tone marks, which derive from the digits 1–4. The rules for denoting tones are shown in the following chart:

"None", that is, no tone marker, is used with the base accent (พื้นเสียง, pheun siang). Mai tri and mai chattawa are only used with mid-class consonants.

Two consonant characters (not diacritics) are used to modify the tone:

ห นำ ho nam, leading ho. A silent, high-class ห "leads" low-class nasal stops (ง, ญ, น and ม) and non-plosives (ว, ย, ร and ล), which have no corresponding high-class phonetic match, into the tone properties of a high-class consonant. In polysyllabic words, an initial mid- or high-class consonant with an implicit vowel similarly "leads" these same low-class consonants into the higher class tone rules, with the tone marker borne by the low-class consonant.

อ นำ o nam, leading o. In four words only, a silent, mid-class อ "leads" low-class ย into mid-class tone rules: อย่า (ya, don't) อยาก (yak, desire) อย่าง (yang, kind, sort, type) อยู่ (yu, stay). Note all four have long-vowel, low-tone siang ek, but อยาก, a dead syllable, needs no tone marker, but the three live syllables all take mai ek.

Exceptions where words are spelled with one tone but pronounced with another often occur in informal conversation (notably the pronouns ฉัน chan and เขา khao, which are both pronounced with a high tone rather than the rising tone indicated by the script). Generally, when such words are recited or read in public, they are pronounced as spelled.

Other diacritics are used to indicate short vowels and silent consonants:

Mai taikhu means "stick that climbs and squats". It is a miniature Thai numeral 8 ๘. Mai taikhu is often used with sara e (เ) and sara ae (แ) in closed syllables.

Thanthakhat means "killing as punishment". Compare Virama.

Fan nu means "rat teeth" and is thought as being placed in combination with short sara i and fong man to form other characters.

Numerals

The Thai script contains decimal numerical digits.

Other symbols

Pai-yan noi and angkhan diao share the same character. Sara a (–ะ) used in combination with other characters is called wisanchani.

Some of the characters can mark the beginning or end of a sentence, chapter, or episode of a story or of a stanza in a poem. These have changed use over time and are becoming uncommon.

Sanskrit and Pali

The Thai script (like all Indic scripts) uses a number of modifications to write Sanskrit and related languages (in particular, Pali). Pali is very closely related to Sanskrit and is the liturgical language of Thai Buddhism. In Thailand, Pali is written and studied using a slightly modified Thai script. The main difference is that each consonant is followed by an implied short a (อะ), not the 'o', or 'ə' of Thai: this short a is never omitted in pronunciation, and if the vowel is not to be pronounced, then a specific symbol must be used, the pinthu อฺ (a solid dot under the consonant). This means that sara a (อะ) is never used when writing Pali, because it is always implied. For example, namo is written นะโม in Thai, but in Pali it is written as นโม, because the อะ is redundant. The Sanskrit word 'mantra' is written มนตร์ in Thai (and therefore pronounced mon), but is written มนฺตฺร in Sanskrit (and therefore pronounced mantra). When writing Pali, only 33 consonants and 12 vowels are used.

This is an example of a Pali text written using the Thai Sanskrit orthography: อรหํ สมฺมาสมฺพุทฺโธ ภควา [arahaṃ sammāsambuddho bhagavā]. Written in modern Thai orthography, this becomes อะระหัง สัมมาสัมพุทโธ ภะคะวา arahang sammasamphuttho phakhawa.

In Thailand, Sanskrit is read out using the Thai values for all the consonants (so ค is read as kha and not [ga]), which makes Thai spoken Sanskrit incomprehensible to sanskritists not trained in Thailand. The Sanskrit values are used in transliteration (without the diacritics), but these values are never actually used when Sanskrit is read out loud in Thailand. The vowels used in Thai are identical to Sanskrit, with the exception of ฤ, ฤๅ, ฦ, and ฦๅ, which are read using their Thai values, not their Sanskrit values. Sanskrit and Pali are not tonal languages, but in Thailand, the Thai tones are used when reading these languages out loud.

In the tables in this section, the Thai value (transliterated according to the Royal Thai system) of each letter is listed first, followed by the IAST value of each letter in square brackets. Remember that in Thailand, the IAST values are never used in pronunciation, but only sometimes in transcriptions (with the diacritics omitted). This disjoint between transcription and spoken value explains the romanisation for Sanskrit names in Thailand that many foreigners find confusing. For example, สุวรรณภูมิ is romanised as Suvarnabhumi, but pronounced su-wan-na-phum. ศรีนครินทร์ is romanised as Srinagarindra but pronounced si-nakha-rin.

Plosives (วรรค vargaḥ)

Plosives (also called stops) are listed in their traditional Sanskrit order, which corresponds to Thai alphabetical order from ก to ม with three exceptions: in Thai, high-class ข is followed by two obsolete characters with no Sanskrit equivalent, high-class ฃ and low-class ฅ; low-class ช is followed by sibilant ซ (low-class equivalent of high-class sibilant ส that follows ศ and ษ.) The table gives the Thai value first, and then the IAST value in square brackets.

None of the Sanskrit plosives are pronounced as the Thai voiced plosives, so these are not represented in the table. While letters are listed here according to their class in Sanskrit, Thai has lost the distinction between many of the consonants. So, while there is a clear distinction between ช and ฌ in Sanskrit, in Thai these two consonants are pronounced identically (including tone). Likewise, the Thai phonemes do not differentiate between the retroflex and dental classes, because Thai has no retroflex consonants. The equivalents of all the retroflex consonants are pronounced identically to their dental counterparts: thus ฏ is pronounced like ต, and ฐ is pronounced like ถ, and so forth.

The Sanskrit unaspirated unvoiced plosives are pronounced as unaspirated unvoiced, whereas Sanskrit aspirated voiced plosives are pronounced as aspirated unvoiced.

Non-plosives (อวรรค avargaḥ)

Semivowels and liquids (กิ่งสระ pha king sara branch vowels") come in Thai alphabetical order after ม, the last of the plosives. The term อวรรค awak means "without a break"; that is, without a plosive.

Sibilants (เสียดแทรก)

เสียดแทรก, pronounced เสียดแซก (siat saek), meaning inserted sound(s), follow the semi-vowel ว in alphabetical order.

Like Sanskrit, Thai has no voiced sibilant (so no 'z' or 'zh'). In modern Thai, the distinction between the three high-class consonants has been lost and all three are pronounced 'sà'; however, foreign words with an sh-sound may still be transcribed as if the Sanskrit values still hold (e.g., ang-grit อังกฤษ for English instead of อังกฤส).

ศ ศาลา (so sala) leads words, as in its example word, ศาลา. The digraph ศรี (Indic sri) is regularly pronounced สี (si), as in Sisaket Province, Thai: ศรีสะเกษ. ษ ฤๅษี (so rue-si) may only lead syllables within a word, as in its example, ฤๅษี, or to end a syllable as in ศรีสะเกษ Sisaket and อังกฤษ Angkrit English. ส เสือ (so suea) spells native Thai words that require a high-class /s/, as well as naturalized Pali/Sanskrit words, such as สารท (สาท) in Thetsakan Sat: เทศกาลสารท (เทด-สะ-กาน-สาท), formerly ศารท (สาท). ซ โซ่ (so so), which follows the similar-appearing ช in Thai alphabetical order, spells words requiring a low-class /s/, as does ทร + vowel. ทร, as in the heading of this section, เสียดแทรก (pronounced เสียดแซก siat saek), when accompanied by a vowel (implicit in ทรง (ซง song an element in forming words used with royalty); a semivowel in ทรวง (ซวง suang chest, heart); or explicit in ทราย (ซาย sai sand). Exceptions to ทร + vowel = /s/ are the prefix โทร- (equivalent to tele- far, pronounced โทระ to-ra), and phonetic re-spellings of English tr- (as in the phonetic respelling of trumpet: ทรัมเพ็ท.) ทร is otherwise pronounced as two syllables ทอระ-, as in ทรมาน (ทอระมาน to-ra-man to torment).

Voiced h (มีหนักมีลม)

ห, a high-class consonant, comes next in alphabetical order, but its low-class equivalent, ฮ, follows similar-appearing อ as the last letter of the Thai alphabet. Like modern Hindi, the voicing has disappeared, and the letter is now pronounced like English 'h'. Like Sanskrit, this letter may only be used to start a syllable, but may not end it. (A popular beer is romanized as Singha, but in Thai is สิงห์, with a mai karan on the ห; correct pronunciation is "sing", but foreigners to Thailand typically say "sing-ha".)

Vowels (สระ)

All consonants have an inherent 'a' sound, and therefore there is no need to use the ะ symbol when writing Sanskrit. The Thai vowels อื, ไอ, ใอ, and so forth, are not used in Sanskrit. The zero consonant, อ, is unique to the Indic alphabets descended from Khmer. When it occurs in Sanskrit, it is always the zero consonant and never the vowel o [ɔː]. Its use in Sanskrit is therefore to write vowels that cannot be otherwise written alone: e.g., อา or อี. When อ is written on its own, then it is a carrier for the implied vowel, a [a] (equivalent to อะ in Thai).

The vowels อำ and อึ occur in Sanskrit, but only as the combination of the pure vowels sara a อา or sara i อิ with nikkhahit อํ.

Other symbols

There are a number of additional symbols only used to write Sanskrit or Pali, and not used in writing Thai.

Nikkhahit นิคหิต (anusvāra)

In Sanskrit, the anusvāra indicates a certain kind of nasal sound. In Thai this is written as an open circle above the consonant. Nasalisation does not occur in Thai, therefore, a nasal stop is always substituted: e.g. ตํ taṃ, is pronounced as ตัง tang by Thai sanskritists. If nikkhahit occurs before a consonant, then Thai uses a nasal stop of the same class: e.g. สํสฺกฺฤตา [saṃskṛta] is read as สันสกฤตา san-sa-krit-ta (The ส following the nikkhahit is a dental-class consonant, therefore the dental-class nasal stop น is used). For this reason, it has been suggested that in Thai, nikkhahit should be listed as a consonant. Nikkhahit นิคหิต occurs as part of the Thai vowels sara am อำ and sara ue อึ.

Pinthu พินทุ (virāma)

อฺ

Because the Thai script is an abugida, a symbol (equivalent to virāma in devanagari) needs to be added to indicate that the implied vowel is not to be pronounced. This is the pinthu, which is a solid dot below the consonant.

Yamakkan ยามักการ

อ๎

Yamakkan is an obsolete symbol used to mark the beginning of consonant clusters: e.g. พ๎ราห๎มณ phramana [brāhmaṇa]. Without the yamakkan, this word would be pronounced pharahamana [barāhamaṇa] instead. This is a feature unique to the Thai script (other Indic scripts use a combination of ligatures, conjuncts or virāma to convey the same information). The symbol is obsolete because pinthu may be used to achieve the same effect: พฺราหฺมณ.

Visarga

The means of recording visarga (final voiceless 'h') in Thai has been lost.

Unicode

Thai script was added to the Unicode Standard in October, 1991 with the release of version 1.0.

The Unicode block for Thai is U+0E00–U+0E7F. It is a verbatim copy of the older TIS-620 character set which encodes the vowels เ, แ, โ, ใ and ไ before the consonants they follow, and thus Thai, Lao, and Tai Viet are the only Brahmic scripts in Unicode that use visual order instead of logical order.