Abstract: The specific German term “Zwölftonreihe” appeared in the first third of the 20th century because of dodecaphony. It significantly developed and experienced meaning extension during the following years. To represent this notion in evolution dynamics, it was necessary to consider it from different perspectives. The article describes the existence and the adaptation of the term “series” in different linguistic traditions; raises the issues of differentiating the meanings “row”, “series” and “set” in the English-language environment, and the terms “series” and “row” in the Russian musicology. The author gives special attention to the problems of defining; points at the difficulties of the first definitions caused by the rootedness of the composer’s thinking in traditions of the classic-romantic system; describes the factors under which the definitions were transformed and corrected. Yet another important aspect of consideration is the difference in understanding a series by the two avant-gardes. The “ultra-thematic” concept of the twelve-tone series (Boulez) with its fundamentally horizontal character was substituted by the “generating” series (without preferrable number of elements), which generated all the derived objects, served as a basis for other parameters and created a structural hierarchy and embraced the composition as a whole.