Passive participles end in -аатай, -оотой, -ээтэй in the modern Buryat language

The introduction of the article considers the ambiguity of morphological voice markers in the Buryat language, the homonymy of voice indicators, often replacing each other without loss of the meaning. We have shown on the examples that this tradition is also characteristic of the texts of medieval monuments of Mongolian writing. The purpose of this article is to characterize the little-studied forms of passive participles end in -аатай, -оотой, -ээтэй, which, unlike the previous affixes, are distinguished by a “hard position”, expressing the meaning of the passive voice in any conditions. The article describes the syncretism of the considered forms, their verbal and attributive features, the criteria for their differentiation. We have made an attempt to determine their part-of- speech affiliation and semantic structure. Failing to find the forms end in -аатай in the writings of the Middle Ages, we have come to the conclusion that they are an innovation developed as a result of a change in object-subject, thematic-rhematic relations in the sentence. Speaking about the prospects, we emphasizes the need to study the actants of the verbal word form in passive construction, in particular the subject complement, which is expressed in the Mongolian languages not only by the ablative case of the subject, but also by the dative-local and even the genitive cases.