Middle Russian language

Middle Russian (среднерусский язык; also Old Great Russian старовеликорусский язык, or Old Russian старорусский язык) is the Russian language of the 14th–17th centuries, from the time of the division of Old Russian into the distinctive languages of Great Russian and West Russian (or Old Belarusian and Old Ukrainian), until the reforms of Peter the Great.

The Central Russian period in the history of the Russian language is further divided into two distinct subperiods: Early Middle Russian (14th–15th centuries) and Late Middle Russian (16th–17th centuries).

Various terms are used in scholarly literature, such as Middle Russian, Old Great Russian, and Old Russian (среднерусский, старовеликорусский, старорусский). These terms are applied primarily to units of language (words) to determine their age or time of written recording.