The article discusses the modus concept of “graduality”, the author gives her own definition of the concept. To describe the structure of the modus concept “graduality”, it is proposed to use cognitive matrix analysis developed by N.N. Boldyrev. The main provisions of this type of analysis are summarized. The author believes that the structure of the concept of “graduality” consists of a core (knowledge that the feature of an object, state or action can vary, that is, manifest itself to varying degrees) and the matrix itself, which includes such conceptual areas as “comparison”, “feature”, “the degree of feature manifestation”, “norm”, “quantity”, “quality”, “assessment”, “language representation”. It is argued that on the basis of the concept of “graduality”, a category of graduality is formed in the language, which, like other language categories, is developing. The paper for the first time expresses the opinion that the formation and development of the category of graduality in the English language have their own conceptual foundations. An attempt is made to identify the conceptual foundations of the development of the modus category of graduality, which comprise the modus concept “graduality” itself, the conceptual basis of the category and its modus character, as well as specific features of the conceptual structure of the semantics of lexical units-members of the language category under analysis.