Merya or Meryanic () is an extinct Finno-Ugric language, which was spoken by the Meryans. Merya began to be assimilated by East Slavs when their territory became incorporated into Kievan Rus' in the 10th century. However some Merya speakers might have even lived in the 18th century. There is also a theory that the word for "Moscow" originates from the Merya language. The Meryan language stretched to the western parts of Vologda Oblast and Moscow.
There is no general agreement on the relationship of Merya to its neighboring Uralic languages.
Rahkonen (2013) argues that the likewise unattested and unclassified-within-Uralic Muromian language was a close relative of Merya, perhaps even a dialect of Meryan.
A probable characteristic of the Merya language, noted by some researchers, is the plural -k, as in Hungarian, while most Uralic languages use -t to mark the plural.
Meryan phonology has been studied only in general terms, with analyses relying on Russian dialects in the Kostroma and Yaroslavl regions. Helimski suggests that Merya likely developed massive reduction of word-final syllables. The Merya language only allowed one consonant at the beginning of words, and likely placed stress on the first syllable of a word. It likely did not feature vowel harmony. The vowels /ö/, /ä/ and /y/ likely existed in the Merya language.
There have been attempts to re-construct Merya based on toponyms, onomastics and words in Russian dialects by O. B. Tkachenko, Arja Ahlqvist and A. K. Matveev among others. The first reconstructions were done in 1985 by O. B. Tkachenko. The latest book about Merya reconstructions was published in 2019. As an example: in Russian toponyms from areas where Merya was spoken, an ending () is regularly seen in names relating to lakes. This also resembles, but does not exactly match, the words for 'lake' in western Uralic languages, such as Finnish , Northern Sami , Erzya (), Meadow Mari () (from a common proto-form ). From these it can be inferred that likely continues the Meryan word for 'lake', which may have had a form such as
According to Rahkonen, in Merya areas there is a word , which is probably cognate with the Komi word () 'middle river', and similar also to an element which appears in Finnish toponyms. From Merya toponyms it can also be seen that words such as 'down' (Finnish: ), 'give' (Finnish: ) existed in the Merya language. From this it can be concluded that Finnish corresponds to or in the Merya language. Another thing that can be observed is the Finnish sound "a" corresponding to a Merya "o", for example a hydronym can be seen, which can be compared to Finnish 'fish'. In the Muroma-Merya territory a word can be observed, which can be compared to Finnic *ülä âÂÂupperâÂÂ.