Abstract
Despite the existence of international standards, recommendations and manuals, medical terminology is characterized by a high percentage of formal-semantic variation. The relevance of the article due to the need to identify the causes of the disorder terminology, to suggest recommendations for its normalization and codification. Source of collection of linguistic material was “Encyclopedic dictionary of medical terms” by V.I. Pokrovsky (Moscow, 2005). The language material was collected by the method of continuous sampling, were analyzed using the historical-etymological method of the analysis of dictionary definitions, the comparative method. One of the most numerous is the variance term, contrasted with the criterion of origin. The novelty of the article is in a functional, pragmatic approach to the term. The study records and analyses of variance, disadvantages of terms and proposes recommendations for future lexicographic practice, taking into account the traditions of science, internal and external causes of language change.