Arin is an extinct Yeniseian language formerly spoken in Russia by the Arin people along the Yenisei River, predominantly on its left shore, between Yeniseysk and Krasnoyarsk, north of the Minusinsk region. However, it has been suggested that the Arin people had historically occupied a larger geographical range. It became extinct in the 18th century, with the death of Arzamas Loskutov, who was an informant for Gerhard Friedrich Müller in 1731, and for a Cossack adventurer named Ivan Kovrigin in 1735.
It is believed that the term Ar or Ara was used by speakers of Arin to refer to themselves.
It is classified as belonging to the Arinic branch, being its only attested language. The closest known relative of Arin, Pumpokol, has been suggested to be similar to the language of the ruling elite of the Xiongnu, as well as that of the Jie ruling class of the Later Zhao dynasty.
Hydronyms associated with Arin have the suffixes , , , , and (meaning "river") and / (meaning "water"). These hydronyms, along with Khanty folklore telling of an eastern people known as the "Ar people", indicate that Arin may have once been spread out as far west as the Ob.
One notable aspect of the Arin phonology is the correspondence of words starting with the word-initial and words in other Yeniseian languages that start with a bare vowel. For example, the Arin word (meaning 'water') corresponds to the Ket word and the Kott word . This feature of Arin allows for far more accurate reconstructing of the Proto-Yeniseian language by historical linguistics, for instance, the Proto-Yeniseian term for "water" is reconstructed as , where the initial *x- could not be inferred if not for Arin attestation.
The vowel system in Arin is as follows:
Consonants in parentheses are sparsely attested or unattested.
There are 11 palatal-nonpalatal consonant oppositions.
Etymological analysis suggests that speakers of the Arin language, as with other members of the Yeniseian people, were bilingual in Siberian Turkic languages; for example, the Arin word (meaning "ore") has been suggested to stem from the Old Turkic compound word (meaning "iron blood"). There are over 400 lexica for the Arin language, recorded in the 18th century.