The given article dwells on the term “concept” as a fundamental category of cognitive semasiology. The study explores the theoretical foundations of cognitive approach to meaning, tracing the emergence and development of the term “concept” from mathematical logic to its current status in cognitive linguistics. Special attention is paid to the distinction between linguistic meaning and mental concept, as well as to the semantic processes underlying terminological polysemy in various professional domains. The article demonstrates that concept, as a unit of mental resources, possesses broader content than linguistic meaning and serves as the primary means of representing cognitive processes in language.