The aim of the interdisciplinary doctoral dissertation is to answer the research question What is a neologism? The research was inspired by the methodology relying on three types of data that J. Bartmiński specifies for studying stereotypes as part of the language picture of the world, i. e. systemic, textual and empirical data. Neologisms are expounded by confronting the linguistic, media and everyday picture of the world with the use an explicative characteristic including connotations of the concept. After introducing the neologism within the context of words marked stylistically with respect to time, the exposition is structured according to (non- homogeneous) criteria, on the basis of which neologisms in the reviewed literature are defined: the criterion of existence, the criterion of time, the lexicographic criterion, the psychological criterion, the structural criterion, the criterion of variety and the criterion of instability and stability. The media image of neologism was examined using the qualitative-quantitative method of content analysis in 93 media texts from 2006 and 2007, and 2016 and 2017. The empirical data were obtained by questionnaires from 2017 and 2018 with 100 respondents aged 11 to 81. In summary, the concept of neologisms is understood as a very heterogeneous one. A list...