The article is a cross-disciplinary study of polysemy applying theoretical, experimental and statistical methods. Although polysemy has been a focus of attention in a variety of papers and books, the phenomenon requires a largely complex approach. The team of authors conducted a multifaceted study that incorporated lexicographic descriptions, statistical analysis, speakers’ surveys, as well as experimental studies of electroencephalograms and eye movements. The study revealed that along with metaphors and metonymy, which are the most common meaning shifts, the development of polysemy also involves a greater number of other shift types. Taken together, these shifts constitute an elaborate hierarchical system and often combine with each other when new meanings are formed. Whether or not the speaker perceives that a word meaning is new, depends on the cognitive distance, which varies for different types of shifts: specifically, a metaphorically formed meaning is perceived to be further away from the original than a metonymic meaning. The way dictionary entries represent lexical meanings is only partly relevant to the structure of the mental lexicon and to the frequency of occurrence of different meanings. A lexicographic representation based on semantic principles is more readily perceived than one based on meaning frequency. The study has invited new interesting questions, such as whether our mental lexicon discriminates between distant and close metonymy.