The article is devoted to the discussion concerning the concept of "art", the analysis of its functioning in the ordinary language and the language of aesthetic theory and art history. The authors share the opinions expressed in the classical works of M. Weitz, who interpreted the category “art” as an open concept, but at the same time they show its extreme ambiguity, which complicates the scientific analysis of artistic culture. In this regard, a number of specific situations are considered in which the meaning of the concept, obvious by virtue of its stereotype, becomes the basis for non-accountable conceptualization of new phenomena coming to the attention of the researcher, thus replacing the primary empirical analysis on which the theory should be based. The article attempts to explicitly highlight the main semantic components of the concept of “art” as it is used in modern aesthetic and art history discourses. This, in particular, is the aesthetic attitude to the objects of the image or to the work itself as a product of creative activity; spiritual specificity; semiotic trait; system of features associated with usual forms of social organization of artistic culture; the system of psychological characteristics (art as a sphere of personal perception, art as figurative thinking); nature of activity in art (art as a fundamentally innovative, non-algorithmic activity); and, finally, a technical attribute - the tendency to reduce art to a fixed, traditional set of techniques: pictorial, sculptural, technique of organizing verbal texts, etc. It is argued that adequate description of the specifics of art is possible only within a hierarchically organized, structurally complex conceptual system (which can be considered as a kind of composed concept). The original basis of this system should be an “open” (but not ambiguous) notion that fixes art as a historical series of genetically related cultural phenomena, but it should be specified more concretely with each set of historical stages with the help of concepts of another type, more rigidly adapted to delineate qualitatively specific phenomena. Probably, these may be concepts of “classic”, closed type (such as concepts describing historically alternating styles).