Thai royal and noble titles
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Thai royal and noble titles are the royal and noble styles signifying relationship to the King introduced by King Trailokanat, who reigned 1448 to 1488. The system is rooted in the Thai language equivalent of feudalism, Sakdina (ศักดินา: literally, power over fields). It is somewhat similar to that of peerage, but is complicated and usually not well understood even by most Thais. A particular title of honor may not be confined to just the beginning or the end of the name, but may be split across the name as will be demonstrated. Those who possessed titles ceased to be designated by personal names and were never spoken of except by the awarded or other similar titles. Another point about the titles is that the King has the power to bestow any title on anybody, regardless of the rule. However, such promotion is personal and the children of the person will not normally benefit from it (see, for example, Phra Worawong Ther Phra Ong Chao).
The King (Sovereign) 
- See also Rama (Kings of Thailand)
There are two titles which can be used for a king (depending on coronation status).
Phrabat Somdet Phra Chao Yu Hua ("Crowned King") 
- Phrabat Somdet Phra Chao Yu Hua (Thai: พระบาทสมเด็จพระเจ้าอยู่หัว) is the normal title used by the kings of Thailand (Siam) after coronation. There are two ways that this title can be used
- It can precede the name of the king – For example
- Phrabat Somdet Phra Chao Yu Hua Bhumibol Adulyadej, in less formal usage than the next possibility.
- It can be split across the name, possibly with omission or modification of the words "Phra Chao Yu Hua".
- Phrabat Somdet Phra Paraminthara Maha Bhumibol Adulyadej
- Phrabat Somdet Phra Paraminthara Maha Prajadhipok Phra Pokklao Chaoyuhua.
Somdet Phra Chao Yu Hua ("Uncrowned King") 
Somdet Phra Chao Yu Hua (สมเด็จพระเจ้าอยู่หัว) is restricted to a king who has not yet gone through coronation, normally precedes the king's name, but once crowned, he will use the title Phrabat Somdet Phra Chao Yu Hua.
Sovereign's Consorts 
Traditionally, titles of the royal wives depended both on their birth titles and royal favour, with only the princesses who are of high birth (Chao Fa, Phra Ong Chao, Mom Chao Ying) taking up titles higher than Chao Chom. There were no clear rules about the hierarchy of the titles above Chao Chom until the time of King Mongkut and even then the titles kept changing over the successive reigns.
The rule about commoners also seems to be evolving over time; it appears that there are no more restrictions keeping a commoner from becoming queen.
Most of the titles listed here are taken from the time King Vajiravudh enacted the Succession Law in 1924.
The Queen 
Only the holders of the titles listed here—all containing the word "rajini" – are the queens in the Western sense, although the concept of queen was only introduced first in the reign of King Rama V. There can be only one "rajini" at a time. The actual title depends on the status of the holder.
Somdet Phra Boromarajininat 
Somdet Phra Boromarajininat (สมเด็จพระบรมราชินีนาถ—the Queen Regent) is the highest rank among the royal wives. This title shows that its holder is a queen who has also acted as a regent for the sovereign. (The word "nat" at the end of the title means "supporter".) This title is normally used in the form of:
- "Somdet + honorific name + Phra boromarajininat"
- "Somdet Phra Nangchao + [name] + Phra boromarajininat".
For example, Queen Sawaphaphongsri (born as Phra Ong Chao Sawaphaphongsri, one of King Chulalongkorn's half-sisters and wives), was given an honorific name of "Phra Sri Patcharindra" when she was invested the queen regent; her name was thus Somdet Phra Sri Patcharindra Phra Boromarajininat. As for the current Queen of Thailand, her name has been retained, thus: Somdet Phra Nangchao Sirikit Phra Boromarajininat.
Somdet Phra Boromarajini 
Somdet Phra Boromarajini (สมเด็จพระบรมราชินี) is the title of a queen who has never acted as a regent. The King conferred this title to Queen Sirikit on his coronation. She was then known as Somdet Phra Nangchao Sirikit Phra Boromarajini.
Somdet Phra Rajini 
Somdet Phra Rajini (สมเด็จพระราชินี) is a somewhat temporary title held by the most prestigious royal wife of a king who has not yet been crowned (see also Somdej Phra Chao Yu Hua, above). This title is appended to the front of the queen's name. Queen Sirikit held this title as "Somdej Phra Rajini Sirikit" for seven days prior to King Bhumibol's coronation.
Other Sovereign's consorts who were born princesses (obsolete) 
The following titles can traditionally only be held by the royal consorts who were born princesses, that is, holding the title of Chao Fa, Phra Ong Chao, or Mom Chao Ying. Together with the queen, they are known as Phra Panya Chao (พระภรรยาเจ้า – 'royal wives').
Somdet Phra Boromarajadevi 
Somdet Phra Boromarajadevi (สมเด็จพระบรมราชเทวี) or HM Queen had been the most prestigious title among the royal wives until King Chulalongkorn created the Rajini (Queen) titles. Only two persons can hold this title at any one time as:-
- Somdet Phra Nangchao Sunandakumariratana Phra Boromarajadevi or Her Majestry Queen Sunandakumariratana (born Phra Ong Chao Sunandakumariratana, another half-sister and wife of King Chulalongkorn). The holder of this title is the first royal consort (as compared to being a queen).
- Somdet Phra Nangchao Savang Vadhana Phra Boromarajadevi or Her Majestry Queen Savang Vadhana (born Phra Ong Chao Savang Vadhana, another half-sister and wife of King Chulalongkorn). The holder of this title is the second royal consort.
Phra Nangchao Phra Rajadevi / Phra Nangchao Phra Akra Rajadevi 
Phra Nangchao ... Phra Rajadevi / Phra Nangchao ... Phra Akra Rajadevi (พระนางเจ้า...พระราชเทวี / พระนางเจ้า...พระอัครราชเทวี) is a lesser title than Somdet Phra Boromarajadevi. Queen Sri Pacharindra (see above) used to hold this title as Phra Nangchao Saovabhabongsri Phra Akra Rajadevi before she was made queen regent.
Phra Nang Thoe 
Phra Nang Thoe (พระนางเธอ) is the title of a royal wife of lesser importance than Phra Nangchao Phra Rajadevi. This title usually prefixes an honorific name, for example: Phra Nang Thoe Laksamilawan, one of the wives of King Vajiravudh. Thoe (เธอ) is a personal pronoun equivalent to she, and, when used as a second- or third-person personal pronoun, stands in T–V distinction with Khun (คุณ).
Phra Akra Chaya Thoe 
Phra Akra Chaya Thoe (พระอัครชายาเธอ) or Her Highness Princess is the next prestigious title to Phra Nang Thoe. In contrast to the previous titles, this title prefixes the previous title of the holder including the royal title from birth, for example:
- Phra Akra Chaya Thoe Phra Ong Chao Ubolratana Narinag or Her Highness Princess Ubolratana Narinag, the Princess Akrarajsuda, the Princess Consort to HM King Chulalongkorn (born Mom Chao Bua Ladawan)
- Phra Akra Chaya Thoe Phra Ong Chao Savabhak Nariratana or Her Highness Princess Savabhak Narinratana, the Princess Consort to HM King Chulalongkorn (born Mom Chao Pieo Ladawan)
- Phra Akra Chaya Thoe Phra Ong Chao Saisavali Bhiromya or Her Highness Princess Saisavali Bhiromya, the Princess Sudhasininart Piyamaharaj Padivarada, the Princess Consort to HM King Chulalongkorn (born Mom Chao Sai Ladwan)
Phra Racha Chaya 
Phra Raja Chaya (พระราชชายา) or Her Highness Princess existed only during the reign of King Chulalongkorn. The only holder of this title was Phra Racha Chaya Chao Dara Rasmi, a princess (Chao Thai เจ้า) Her Highness Princess Dara Rasmi, the Princess Consort to HM King Chulalongkorn from the Thipjakrathiwong dynasty of Chiang Mai. Technically, she was a "commoner" from the point of view of the Chakri dynasty, and was thus initially appointed as a Chao Chom. She was later 'ennobled' and given this particular title, which, although higher in status than Chao Chom, was still the most junior among the royal wives who were born princesses.
Sovereign's consorts who were born commoners (obsolete) 
Chao Chom 
Chao Chom (เจ้าจอม) is the only title held by the royal wives who were born as commoners (Mom Rajawongse and below). If they were successful in producing a child for the king, the title would be changed to Chao Chom Manda (เจ้าจอมมารดา). This title also prefixes previous royal titles; for example: Chao Chom Mom Rajawongse Sadab (born Mom Rajawongse Sadab Laddawan).
Descendants of a Sovereign 
Generally speaking, a child of a holder of the following titles inherits the title which is one step below. However, the inheritance is on the male line only: a female Mom Rajawongse married to a plain commoner would produce a child with no title. (However, see Khun (courtesy title) below.) Tradition also requires that a princess asks for royal permission and surrenders her title if she wishes to marry a man of lesser title, e.g. if a female Chao Fa wishes to marry a male Mom Rajawongse. This happened in recent time to Chao Fa Ubolratana Rajakunya, the daughter of the current king, who had to give up her title of Chao Fa to marry a commoner (a US citizen). She still retains the style of "Tunkramom Ying", though. However, her sister, Chao Fa Chulabhonwalailak, was granted permission by the King to keep her title when she married Sqn. Ldr. Weerayut Disayasirin, a commoner.
Royal Princes and Princesses 
Holders of these titles are still considered royal as they are at most two generations down from a king. Collectively, those who are children of a king are called "Luk Luang" (ลูก หลวง – 'royal children') and those who are grandchildren of a king are called "Laan Luang" (หลานหลวง – 'royal grandchildren'). In English translation, they are normally called "prince" or princess". Special forms of language are also used when one wishes to speak to them, although the language is less elaborate than when speaking to the king or the queen. A male Luk Luang who does not accede to the throne would also start a new royal surname, which normally reflects his birth name (as opposed to an honorific name given later). The surname can be used by his wife if she is a commoner by birth, possibly with Na Ayudhya added if she has no noble title. It is otherwise not normally used until his children or grandchildren first hold the title of Mom Chao, when the surname will first appear in their names.
Chao Fa (HRH Prince) (HRH Princess) 
- Chao Fa of the First Class (เจ้าฟ้าชั้นเอก – Chao Fa Chan Ek). These are the prince/princesses born to the queen or to a royal consort who is also a Luk Luang or royal children. They would traditionally be referred to as "Tunkramomfa Chai(m)/Tunkramomfa Ying(f)" (ทูลกระหม่อมฟ้า ชาย/ทูลกระหม่อมฟ้า หญิง), although nowadays they are more commonly called Chao Fa.
- Chao Fa of the Second Class (เจ้าฟ้าชั้นโท – Chao Fa Chan Tho). These are the princes/princesses born to a royal consort who is also a Laan Luang or royal grand children. They would traditionally be referred to as "Somdet Chai(m)/Somdet Ying(f)" (สมเด็จชาย/สมเด็จหญิง).
- Chao Fa of the Third Class (เจ้าฟ้าชั้นตรี – Chao Fa Chan Tri). These are the princes/princesses that are specially appointed or born to Krom Phrarachawangbowon (กรมพระราชวังบวร).
Three (3) persons currently hold Chao Fa rank (highest royal rank after the King and Queen):
- HRH Prince Maha Vajiralongkorn (born 1952) (only son of King Rama IX)
- HRH Princess Maha Chakri Sirindhorn (born 1955) (2nd born daughter of King Rama IX)
- HRH Princess Chulabhorn (born 1957) (youngest daughter of King Rama IX)
- [NOTE: Princess Ubol Ratana (eldest child of HM King Rama IX) lost her Chao Fa (HRH) title when she married commoner Peter Ladd Jensen.]
- [NOTE: HRH Princess Galyani Vadhana (born 1923) (elder sister of HM King Bhumibol Adulyadej (Rama IX)) died 2 January 2008.]
- [NOTE: HRH Princess Bejaratana (born 1925) (daughter of the late King Rama VI) died 27 July 2011.]
Phra Ong Chao (HRH Prince) (HRH Princess) /// (HH Prince) (HH Princess) 
Phra Ong Chao (พระองค์เจ้า) is a lesser class of the princes/princesses than Chao Fa. They could be either:
Phra Chao Boromawongse Ther Phra Ong Chao (พระเจ้าบรมวงศ์เธอ พระองค์เจ้า)"His/Her Royal Highness" These are the princes/princesses who are of Phra Ong Chao rank (instead of higher Chao Fa rank) by birth (i.e., children of a king and a Chao Chom Manda (a consort who was born commoner) or who are specially promoted by a king to this high rank.
Phra Chao Worawongse Ther Phra Ong Chao (พระเจ้าวรวงศ์เธอ พระองค์เจ้า) "His/Her Royal Highness" Generally, these are the princes/princesses who are grandchildren of a king or who are specially promoted by a king to this rank. The categories are as follows:
- Children of a Chao Fa and a royal princess (Phra Ong Chao, or Mom Chao Ying). In turn, the children of this rank may hold the title of Mom Chao if royal permission is granted.
- Children of a Phra Chao Boromawongse Ther Phra Ong Chao and a royal princess whose rank is Phra Ong Chao.
- Mom Chao to whom the king granted a special promotion to become a Pra Chao Worawongse Ther Pra Ong Chao (e.g. Mom Chao Chula-Chakrabongse's appointment to Phra Chao Worawongse Ther Phra Ong Chao rank by H.M. King Rama VI). However, the children of this category of Phra Ong Chao will be treated as in the normal course as children of a Mom Chao and will hold the title of Mom Rajawongse.
At least seven persons currently hold Phra Ong Chao rank (mid level royal rank) including:
- HRH Princess Srirasmi (born 1971) (wife of The Crown Prince)
- HRH Princess Soamsavali (born 1957) (previous wife of The Crown Prince)
- HRH Princess Bajrakitiyabha (born 1978) (daughter of The Crown Prince and HRH Princess Soamsavali)
- HRH Princess Siriwannawari (born 1987) (daughter of The Crown Prince and Mom Yuvadhida)
- HRH Prince Dipangkorn Rasmijoti (born 2005) (son of The Crown Prince and HRH Princess Srirasmi)
- HRH Princess Siribhachudhabhorn (born 1982) (daughter of HRH Princess Chulabhorn and Air Vice Marshall Virayudh)
- HRH Princess Adityadhornkitikhun (born 1984) (daughter of HRH Princess Chulabhorn and Air Vice Marshall Virayudh)
Phra Worawong Ther Phra Ong Chao (พระวรวงศ์เธอ พระองค์เจ้า) "His/Her Highness". These are:
- Mom Chao whom the king granted this higher title, either as recognition of merit, or as a special favour. An example of this is Phra Worawong Ther Phra Ong Chao Nakkatra Mongkol Kromma Mhun Chandaburi Suranat, father of Queen Sirikit, who was born Mom Chao Nakkatra Mongkol Kitiyakorn (note that his surname is omitted now that he has become a Phra Ong Chao). This title is however personal to the recipient, and his children would still be treated as children of a Mom Chao as usual (i.e. inherit the title of Mom Rajawongse rather than Mom Chao).
- Children of a Somdej Chao Fa whose grandmothers were queens of Rama V received the royal permission of H.M. King Rama VII to hold the title of Phra Worawongse Ther Pra Ong Chao even though their mothers were commoners. An example of this is Phra Worawongse Ther Pra Ong Chao Bhumibhol Adulyadej, currently H.M. King Rama IX who is the son of Somdej Phra Boromawongse Ther Chao Fa Kroma Luang Songkhlanakarin and Mom Sangwal who was a commoner.
Mom Chao (His/Her Serene Highness Prince/Princess) 
Mom Chao(m)/Mom Chao Ying(f) (หม่อมเจ้า/หม่อมเจ้าหญิง, abbreviated in Thai as ม.จ. or in English as M.C.) is the most junior class still considered royalty. This is normally when surnames first appear among royal lineages. In English this rank is translated as "His or Her Serene Highness." They are either:
Informally, they are styled Than Chai(m).../Than Ying(f)... (ท่านชาย.../ท่านหญิง...).
There were a few dozen persons living As of 2008[update] who held Mom Chao (most junior royal) rank, including:
Prince Bhisadej Rajani (born 1922) (son of HRH Prince Bidyalongkorn (a grandson of Vice-King Pinklao, who was a brother of King Rama IV) and younger brother of Princess Vibhavadi RANGSIT (wife of Prince Piya Rangsit, a grandson of King Rama V)). Princess Vibhavadi Rangsit was posthumously elevated to the rank of HRH (Phra Ong Chao) following her tragic death in service to the country)
Princess Bhandu Savali YUGALA (born 1933) (daughter of HRH Prince Bhanubandhu YUGALA, a grandson of King Rama V) (sister-in-law to HM Queen Sirikit and mother to HRH Princess Soamsavali)
Prince Bhuribandhu YUGALA (born 1934) (son of HRH Prince Bhanubandhu YUGALA, a grandson of King Rama V)
Princess Rangsi Nobhadol YUGALA (born 1937) (daughter of HRH Prince Bhanubandhu YUGALA, a grandson of King Rama V)
Prince Navabarnsa YUGALA (born 1978) (son of HRH Prince Bhanubandhu YUGALA, a grandson of King Rama V)
Princess Bhanuma YUGALA (born 1981) (daughter of HRH Prince Bhanubandhu YUGALA, a grandson of King Rama V)
Prince Mongolchalerm YUGALA (born 1936) (son of HRH Prince Chalermbala YUGALA, a grandson of King Rama V)
Princess Sri Savangwongse YUGALA (born 1946) (daughter of HRH Prince Chalermbala YUGALA, a grandson of King Rama V)
Prince Bhisadej Buddhasiri YUGALA (born 1944) (son of HRH Prince Chalermbala YUGALA, a grandson of King Rama V)
Prince Chalermsuk YUGALA (born 1950) (son of HRH Prince Chalermbala YUGALA, a grandson of King Rama V)
Prince Dighambara YUGALA (born 1951) (son of HRH Prince Chalermbala YUGALA, a grandson of King Rama V)
Princess Bhumari YUGALA (born 1939) (daughter of HRH Prince Anusara YUGALA, a grandson of King Rama V)
Princess Malini Mongol YUGALA (born 1940) (daughter of HRH Prince Anusara YUGALA, a grandson of King Rama V)
Princess Padamon Rangsi YUGALA (born 1941) (daughter of HRH Prince Anusara YUGALA, a grandson of King Rama V)
Prince Chatrichalerm Yugala or YUKOL (born 1942) (son of HRH Prince Anusara YUGALA, a grandson of King Rama V) (he is a movie director, e.g. The Legend of Suriyothai and King Naresuan the Great)
Prince Chulcherm Yugala YUGALA (born 1947) (son of HRH Prince Anusara YUGALA, a grandson of King Rama V)
Princess Nobhadol Chalerm Sri YUGALA (born 1953) (daughter of HRH Prince Anusara YUGALA, a grandson of King Rama V)
"Titled commoners" 
More distant royal progeny, starting from the children of male Mom Chao, are considered commoners. However, these commoners have titles (or a surname suffix) to indicate that their ancestry can be traced back to a king.
Mom Rajawongse 
Mom Rajawongse (หม่อมราชวงศ์, RTGS: Mom Ratchawong; abbreviated in Thai as ม.ร.ว. or in English as M.R. and also translated into English as The Honourable) is the title assumed by children of male Mom Chao. The title is pronounced "Mom Rachawong". Informally, they may be styled as Khun Chai(m).../Khunying(f)... (คุณชาย.../คุณหญิง...). (Khunying is also a formal title given to commoner married ladies who have been granted at least the Order of Chulachomklao, Fourth Class.) Holders of this title are occasionally erroneously referred to as princes/princesses in older English translated older documents; it is more common these days to use the correct title of "Mom Rajawongse".
Mom Luang 
Mom Luang (หม่อมหลวง, abbreviated in Thai as ม.ล. and sometimes in English as M.L. and translated into English as The Honourable) are the last royal descendants still retaining a title. Mom Luang titles are conferred on children of male Mom Rajawongse. Colloquially, though incorrectly, they are sometimes addressed as "Mom"; the correct informal address is "Khun".
Na Ayudhya 
The children and subsequent descendants of a male Mom Luang do not hold any title. However, they append the words "Na Ayudhya" (ณ อยุธยา) to their surname, signifying they are descended from a royal blood line.
Miscellaneous titles of royal descendants (obsolete) 
Mom (royalty) 
Mom (หม่อม) has a rather ill-defined status among the hierarchy of the royal titles. A holder of this title may be either:
- a person of Mom Rajawongse rank, who has been granted this "Mom" title by the king in recognition of his merit. Technically, this is a feudal lifetime title, equivalent to the title Phraya granted to commoners; it is thus written without a space. The title is granted together with an honorific name, and is used without a surname, for example: Mom Anuwatworapong (หม่อมอนุวัตรวรพงษ์), who was born as Mom Rajawongse Singhanad Pramoj (หม่อมราชวงศ์ สิงหนัด ปราโมช).
- a former prince whose title has been stripped off as a punishment. He would still be known as Mom [name].
Prince's wife's title (unless otherwise elevated by the Sovereign) 
Wives of the princes also have titles. Again, this depends on the titles of both sides.
Phra Chaya 
Phra Chaya (พระชายา) is a princess in her own right who is married to either Chao Fa or a Phra Ong Chao ranked royal prince (HRH Prince). She retains her own title. When referring to her as a wife of the prince, she may be called "Phra Chaya Nai [Husband's name]".
Chaya (ชายา) is a princess in her own right who is married to a Mom Chao (HSH Prince). Again, she would retain her own title. When referring to her as a wife of the prince, she may be called "Chaya Nai [Husband's name]".
Mom (wife) 
Mom (หม่อม) in this context is a commoner married to a prince. She will use this title to prefix her name and add the word Na Ayudhya to her new surname, for example: Mom Srirasmi Mahidol Na Ayudhya (a wife of Chao Fa Maha Vajiralongkorn, whose surname is Mahidol).
After the birth of HRH Prince Dipangkorn Rasmijoti, Mom Srirasmi Mahidol Na Ayudhya was elevated by King Rama IX to "Phra Ong Chao" rank (i.e., Phra Chao Worawong Ther Phra Ong Chao Srirasmi Phraworachaya nai Somdej Phraborom Orasathiraj Siammakut Rajakumari (HRH Princess Srirasmi, the Royal Consort of His Royal Highness Crown Prince Maha Vajiralongkorn)).
Krom (กรม) is a term of Khmer language origin used as a prefix to designate a government department, bureau, or military regiment. Historically, it was used to designate a prince or princess of the blood appointed (ทรงกรม Song Krom) as head of the like. There are five classes of such princes in ascending order: kromma muen (กรมหมื่น), kromma khun (กรมขุน), kromma luang (กรมหลวง), kromma phra (กรมพระ), krom phraya (กรมพระยา), and krom kritsadika (กรมกฤษฎีกา). How krom is used in titles is more fully discussed in "5 feudal titles for prince/princess," below. Note that those who possessed titles ceased to be designated by any personal names. See also the department of Kromma Tha, and “Krom Phra Khlang”.
Feudal lifetime titles 
Feudal titles were granted until just after the Siamese revolution of 1932 brought an end to absolute monarchy, and for that matter, feudalism in Thailand. The titles are now obsolete, although on very rare occasions the king may still grant an honorary feudal title to a royal. The latest title granted was "Kromma Luang Narathiwat Rajanakarin" (translated as "Princess of Narathiwat", literally "Viscountess of Narathiwat, Ruler of the Royal City") to the late Princess Galyani Vadhana, the King's sister (Somdet Phra Chao Phi Nang Thoe Chao Fa Galyani Vadhana).
The full title granted consists of a prefix, which signifies the rank (บรรดาศักดิ์ – Bandasak), and an honorific name (ราชทินนาม – Ratchathinnanam), which can well be recycled. Taking the above example, the rank was "Luang" and the honorific name was "Narathiwat Rajanakarin". The appointee would use the full title in place of his names. However, as the honorific name can be repeated, when referring to a previous title holder, his former name may be written in a bracket to avoid confusion, for example: Phraya Kosathibodi (Lek) and Phraya Kosathibodi (Pan).
It is again a bit more complicated with the Chao Fa and Phra Ong Chao. If given a feudal title, they are said to "Song Krom" (ทรงกรม – lit.: "take department", but probably more semantically related to "take office"). The title is prefixed with the word "Krom", appended to (not replacing) the former princely title. For example, the full title of the King's sister is "Somdej Phra Chao Pheenang Ther Chao Fa Galyani Vadhana Kromma Luang Narathivat Rajanakarin. Nevertheless, it is the princely title which will be more frequently omitted when contracting the title e.g. Somdej Phra Chao Boromawong Ther Krom Phraya Damrong Rajanubhab (born Phra Ong Chao Disuankumaan). There are 5 feudal titles for prince/princess
- Somdet Krom Phraya (from Rama VI) or Krom Somdet Phra (Rama IV – Rama V) (สมเด็จกรมพระยา หรือ กรมสมเด็จพระ). in case of the female (ฝ่ายใน) this title will be "Somdet Phra" (สมเด็จพระ). The title "Somdet Phra" is usually grant to the queen mother or princess mother of the king, except two person : HRH Princess Maha Chakri Sirindhorn (Somdet Phra Theprat Ratsuda Chao Fa Maha Chakri Sirindhorn Ratthasima Khunakon Piyachat Sayam Borommaratchakumari) (HM The King Rama IX 's daughter) and HRH Mahidol Adulyadej, Prince of Songkhla (Somdet Pramahitathibet Adulyadejvikrom Prabarommarajajanok) (Prince Father of HM The King Rama IX, his rank equivalent to the "Somdet Phra Bawornrajchao" (Vice King or Front Palace))
- Kromma Phra (กรมพระ)
- Kromma Luang (กรมหลวง)
- Kromma Khun (กรมขุน) Chao Fa starts from this title
- Kromma Muen (กรมหมื่น) Phra Ong Chao starts from this title
Since the time of King Chulalongkorn, the honorific titles given to the royalties normally incorporate a city name or its modified form, and the holders are known in English as the Prince or Princess of that city.
Feudal titles are not inheritable.
Feudal lifetime titles for male commoners (all obsolete) 
These titles were given only to males and not inheritable much like a life peerage. European equivalents were also used on diplomatic missions. While all are obsolete as feudal titles, note that Phan, Nai, and Phrai have modern word usages.
Somdet Chao Phraya 
Somdet Chao Phraya (สมเด็จเจ้าพระยา) is the most senior among the ranks. It is awarded under extraordinary circumstances only to those with great achievements. This title is equivalent to that of a prince or Grand Duke.
There have only been four persons in Siam's history to be elevated to this title. The first was granted by King Taksin of Thonburi to Chao Phraya Chakri who later become King Rama I of Bangkok; three more were granted to members of the House of Bunnag: two by King Rama IV and the last by King Rama V.
Chao Phraya 
Chao Phraya (เจ้าพระยา) is the most senior rank commonly granted. It is normally bestowed upon commoners who served as Ministers of State. The title has been awarded to at least one foreigner: Chao Phraya Abhai Raja (Thai: เจ้าพระยาอภัยราชาสยามานุกูลกิจ.) Holders of this title are informally addressed and referred to as "Chao Khun" (เจ้าคุณ) (2nd person: Chao Khun; 3rd person: Chao Khun + [honorific name]). This title is equivalent to Duke. The Chao Phraya River that runs through Bangkok was once known simply as Menam (แม่น้ำ maenam,) the generic term for river; the full name signifies that it is the chief river in the kingdom.
Phraya (พระยา) is next in term of seniority. Similar to Chao Phraya, holders of this title are also informally addressed and referred to as "Chao Khun" (เจ้าคุณ). This title is equivalent to Marquess or Marquis. For an ancient synonym, see Thao.
Phra and Jamuen (or Phranai) 
Phra (พระ) is further down the line. Holders of this title are informally addressed and referred to as "Khun Phra" (คุณพระ) (2nd person: Khun Phra; 3rd person: Khun Phra + [honorific name]). Jamuen (จมื่น หรือ พระนาย) is a senior title equivalent to Phra, given only to the Head of the king's servants (มหาดเล็ก). The European equivalent to this title is Count or Earl.
Luang (หลวง). Still further down the line, holders of this title are informally addressed and referred to as "Khun Luang" (คุณหลวง) (2nd person: Khun Luang; 3rd person: Khun Luang + [honorific name]). Equivalent to viscount.
Khun (ขุน). Pronounced with rising tone, as opposed to mid-tone courtesy title Khun (คุณ). Holders of this title were informally addressed as "Than Khun" (ท่านขุน). The last living holder was believed to be Pol Maj-Gen. Khun Phantharak Rajadej (Butr Phantharak), who died in 2006 at age 103. Equivalent to Baron. In older usage, khun was used for a ruler of a fortified town and its surrounding villages, together called a mueang; with the prefix pho (พ่อ "father") appears as Pho Khun.
Muen (หมื่น), the Thai numeral 10,000, refers to Muen Nai (มูลนาย) or Chao Khun Muen Nai (เจ้าขุนมูลนาย), who in Ayutthayan times were charged with the oversight of phrai (see below) who themselves were registered in lists called hang wao (หางว่าว 'kite-tails', suggesting their inordinate length.)
Phan (พัน ), the Thai numeral thousand, is a lower rank, and not considered very noble. This title was formerly held by junior officials, especially those in rural areas. In the current military ranks of the Thai armed forces, Phan Ek (พันเอก) is First of 1,000 or Colonel; Phan Tho (พันโท) Second of 1,000, a Lieutenant Colonel.
Nai (นาย) is the most junior of the ranks, – one step up from Phrai plain commoner – and not normally considered noble. Nowadays used as an equivalent for Mister, with Nang Sao (นางสาว) the equivalent of Miss and Nang (นาง) the equivalent of Mrs. or Ms. Related terms: Chao Nai (เจ้านาย) either royalty or boss; Meun Nai (มูลนาย) and Chao Khun Moon Nai (เจ้าขุนมูลนาย), master (of Phrai.)
Phrai (ไพร่) – Common people having no sakdina – above the seven categories of slave (ทาส) but subject to corvée for three months out of a year. Related terms: Phrai Luang, (ไพร่หลวง) in service to the sovereign; Phrai Som (ไพร่สม), under a master; Phrai Tahan (ไพร่ทหาร), soldier; Phrai Suay (ไพร่ส่วย) making payment in kind (cattle) in lieu of service. After the abolition of corvée and slavery in 1905, the term fell into disuse as unmannerly in favor of khon saman (คนสามัญ) commoner; khon thammada (คนธรรมดา) ordinary person of no specified social status; or khon pokati (คนปกติ) normal person. Compare churl and the trifunctional hypothesis of Proto-Indo-European society. Phrai reemerged during the 2008–2010 Thai political crisis as an epithet used for (and by) the Redshirt protesters.
Lifetime conferred titles for female commoners (still in use) 
King Rama V created the titles currently in use for women. The present King (Bhumibhol, King Rama IX), usually, grants the titles for women on the coronation day (5 May) every year. These are the only titles for commoners that have survived in modern day usage, since the titles for men are no longer in use. (See also Nai, above, for Miss and Mrs.)
Than Phuying 
Than Phuying (ท่านผู้หญิง) is the highest conferred non-inheritable lifetime title for a non-royal woman and ranks higher than the non-royal titles of "Mom Rajawong" or "Mom Luang" obtained by birth. Such title is sometimes roughly translated as Dame or Lady.
Khunying (คุณหญิง) is a conferred non-inheritable lifetime title for a married non-royal woman ranking lower than a conferred title of "Than Phuying" or a birth non-royal title of "Mom Rajawong", but ranking higher than a birth non-royal title of "Mom Luang". Such title of "Khunying" is sometimes roughly translated as Dame or Lady. An unmarried woman with a conferred title is styled Khun (courtesy title) (คุณ).
Khun (courtesy title) 
Khun (คุณ) is a courtesy title pronounced with a mid tone and should not be confused with the similarly spelled tree; or with the feudal title Khun (ขุน) that is pronounced in rising tone. The courtesy title is used for children born to a noble mother who gave up her title to marry a man of lesser rank, a well-known example being Khun Poom Jensen. Today, this word is used informally to courteously address virtually anyone apart from those who actually hold a title of Mom Rajawongse or higher. It stands in T–V distinction to thoe (เธอ).
See also 
- Thai honorifics
- Thai military ranks
- Hereditary titles
- Mandala (Southeast Asian history)
- Rama (Kings of Thailand)
- Regnal name
- Royal and noble ranks
- Royal and noble styles (European)
- Saopha (Shan States)
- Style (manner of address)
- Title of honor
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