Bulgar (also known as Bulghar, Bolgar, or Bolghar) is an extinct Oghuric Turkic language spoken by the Bulgars.

The name is derived from the Bulgars, a tribal association that established the Bulgar state known as Old Great Bulgaria in the mid-7th century, giving rise to the Danubian Bulgaria by the 680s.^[1][2][3] While the language was extinct in Danubian Bulgaria (in favour of Old Bulgarian), it persisted in Volga Bulgaria, eventually being replaced by the modern Chuvash language.^[4][5][6]

Other than Chuvash, Bulgar is the only language to be definitively classified as an Oghur Turkic language. The inclusion of other languages such as Hunnish, Khazar and Sabir within Oghur Turkic remains speculative owing to the paucity of historical records. Some scholars suggest Hunnish had strong ties with Bulgar and to modern Chuvash^[7] and refer to this extended grouping as separate Hunno-Bulgar languages.^[8][9]

Mainstream scholarship places Bulgar among the "Lir" branch of Turkic languages referred to as Oghur Turkic, Lir-Turkic or, indeed, "Bulgar Turkic", as opposed to the "Shaz"-type of Common Turkic. The "Lir" branch is characterized by sound correspondences such as Oghuric /r/ versus Common Turkic (or Shaz-Turkic) /z/ and Oghuric /l/ versus Common Turkic (Shaz-Turkic) /š/.^[1][3][10] As was stated by Al-Istakhri (Х c. AD), "The language of the Khazars is different than the language of the Turks and the Persians, nor does a tongue of (any) group of humanity have anything in common with it and the language of the Bulgars is like the language of the Khazars, but the Burtas have another language."^[11]

The only surviving language from this linguistic group is Chuvash.^[12] He concludes that the language of the Bulgars was from the family of the Hunnic languages, as he calls the Oghur languages.^[13] According to the Bulgarian Antoaneta Granberg, the Hunno-Bulgar linguistic situation is further complicated by the extensive migration of nomadic communities of Hunnic and Oghuric peoples from East to West. This migration brought them into contact with a variety of different lands, neighbors, cultures, and languages, including China and Rome. Linguistic individuation of the Hunno-Bulgaric language family has yet to be conclusively established. A Hunno-Bulgar language is believed to have formed on the North-Western borders of China in the 3rd-5th c. BC.^[14]

The language of the Danube Bulgars (or Danubian Bulgar) is recorded in a small number of inscriptions, which are found in Pliska, the first capital of First Bulgarian Empire, and in the rock churches near the town of Murfatlar, in present-day Romania. Some of these inscriptions are written in the Greek characters, others in the Kuban alphabet which is a variant of Orkhon script. Most of these appear to have been of a private character (oaths, dedications, inscriptions on grave stones) and some were court inventories. Although attempts at decipherment have been made, none of them has gained wide acceptance. These inscriptions in Danubian Bulgar are found along with other, official ones written in Greek; which was used as the official state language of the First Bulgarian Empire until the end of the ninth century, when it was replaced by Old Bulgarian (also called Old Church Slavonic, later Slavonic).^[30]

The language of the Danubian Bulgars is also known from a small number of loanwords in the Old Bulgarian language, as well as terms occurring in Bulgar Greek-language inscriptions, contemporary Byzantine texts,^[31] and later Slavonic Old Bulgarian texts. Most of these words designate titles and other concepts concerning the affairs of state, including the official 12-year cyclic calendar (as used in the Nominalia of the Bulgarian khans). The language became extinct in Danubian Bulgaria in the ninth century as the Bulgar nobility became gradually Slavicized after the Old Bulgarian tongue was declared as official in 893.

The language spoken by the population of Volga Bulgaria is known as Volga-Bulgar. There are a number of surviving inscriptions in Volga-Bulgar, some of which are written with Arabic letters, alongside the continuing use of Orkhon script. These are all largely decipherable. That language persisted until the 13th or the 14th century. In that region, it may have ultimately given rise to the Chuvash language, which is most closely related to it^[33] and which is classified as the only surviving member of a separate "Oghur-Turkic" (or Lir-Turkic) branch of the Turkic languages, to which Bulgar is also considered to have belonged (see above).^[1][2][34] Still, the precise position of Chuvash within the Oghur family of languages is a matter of dispute among linguists. Since the comparative material attributable to the extinct members of Oghuric (Khazar and Bulgar) is scant, little is known about any precise interrelation of these languages and it is a matter of dispute whether Chuvash, the only "Lir"-type language with sufficient extant linguistic material, might be the daughter language of any of these or just a sister branch.^[10]

• Buyla inscription