Preliminary studies of material covering 2,500 of the most frequent lexemes in Silesian literature made it possible to identify six main thematic domains. Thus, the most numerous words are the lexical forms related to the functioning of humans: to the mental and emotional dimension (629 lexemes) and the biological dimension (490 lexemes). Other forms are related to human participation in social life (465), the material world and ways of interacting with it (384), space and ways of moving in it (261), time and temporal features (151). The analysis of the Silesian lexicon proved the existence of intellectualised vocabulary (abstract forms, terms), numerous synonymous forms and a high frequency of Germanisms (14%). A noticeable part of the Silesian lexicon (15%) is entirely foreign to contemporary standard Polish language. The remaining group of Silesian lexemes (except for a small number of indeclinable words) differs to a greater or lesser extent from their Polish counterparts — mainly in terms of their phonetics and inflection.