The article presents an analysis of the jargon lexeme ChSV, which entered the Russian language in the 1990s as an abbreviation of the esotericism chuvstvo sobstvennoi vazhnosti ("self-importance") from the translation of books by K. Castaneda. Using RNC, GICR, “natural corpora” of Yandex and Google, examples from speech and private correspondence, as well as survey data of 75 informants of different ages in 2025, the authors present the analysis of the lexeme from the point of view of nanodiachrony, semantics, and syntax. It was revealed that ChSV has three meanings: the initial "self-importance" (He has ChSV) and the later metonymic transference "proud person" (He is ChSV) and "proud" (ChSV person) (the latter two are difficult to distinguish due to the immutability of the lexeme). The lexeme entered the speech of the Runet with the appearance of social networks in 2002, and its peak use occurred in 2016. However, the word is still actively living in certain adolescent microsociums, while for many representatives of the older generation who used the word ten years ago, it seems outdated and non-existent. The fixation of the lexeme in the modern language is due to the fact that it fills a semantic gap, representing a non-sharply offensive negative characteristic of a person that is necessary when communicating on the Runet and within youth microgroups. For the authors, the lexeme analysis serves as an occasion to draw the attention of lexicologists to the problem of generational interaction in relation to jargonisms. The analysis presented in the article shows that the knowledge of a particular meaning and the perception of the ChSV lexeme as an abbreviation largely depends on the generation: native speakers born in 1982-1990 take only the original meaning, and native speakers born in 2010 and younger people know only the second one. Surprisingly, the meaning and syntactic constructions with the word peculiar to the speech of the younger ones seem impossible to the elders and vice versa. This article presents the first part of the study of the lexeme ChSV. The second one will be devoted to this unit as an abbreviation and will show how, in the course of time and with the change of generations and meaning, the motivation of the word disappears.