Abstract: Based on the example of synonymic chains as part of the lexical-thematic group of denominations of weapon in the Middle High German epic, this article demonstrates the use of the stability parameter of lexical synonyms for studying the evolutionary processes in language lexicon. Correlation between the stability parameter and the sphere of historical lexicology is drawn based on the concepts of lexical, nominative and semantic stability of the word offer by I. A. Ershova. The concept of word stability implies the presence of at least two chronological periods for comparison, which includes the stability parameter into the paradigm of methods for studying the evolution of language lexicon. This research highlights two stages in the history of German literature of the High Middle Ages: pre-courtly epic and courtly romance. Examination of the stability of lexical synonyms in the language of the Middle High German epic reveals the functionality and restrictions of this method of studying the evolution of lexicon. Reduction of the absolute values of stability parameter of the separate elements of synonymic chain to the parameter of relative stability of the entire row provides a systemic description of the evolution of lexical synonymy in the Middle High German language. Comparison of the three types of stability for different synonymic chains with transformations within their structure alongside the synonyms leads to the conclusion on the role of stability parameter in studying the evolutionary processes in lexicon as a manifestation of their presence or absence, as well as a means for determining the development vector of language vocabulary. The restrictions of this method are associated with the need to prove or expand the data on evolution of lexicon using cultural-historical and stylistic analysis.