Evolution of the dative, instrumental and locative plural forms in *ŏ/*jŏ-declension based on Old Russian monuments of business writing

Abstract

The article examines one of the morphological innovations in Old Russian noun declension system, so-called the a-expansion, as a result of which the words of all declensions acquired inflections with the formant -a- (-амъ, -ами, -ахъ) in the dative, instrumental and locative plural forms. An analysis of the relevant *ŏ/*jŏ-stem noun forms, which were found in the five studied corpora of Old Russian business writing monuments of different geographical origin, made it possible to reveal several patterns in the development of this process that are significant for historical morphology. Thus, the data show that the a-expansion either was evolving more slowly in the instrumental case than in the dative and locative cases or was less often reflected in writing. Based on the studied material, the article concludes that neuter nouns could succumb to the a-expansion faster than masculine words. In addition, the data of the studied texts allowed assuming that the a-expansion began earlier and was evolving faster in the northwest, while in the central zone this process proceeded slower.