Introduction. The term and the definition of the boundaries of colloquialism confuses scientists and generates different opinions. Some scientists define colloquialism in a narrower sense, referring it to a stylistically reduced vocabulary, which is the opposite of the literary norm. Thus, colloquialisms include mostly substandard vocabulary, which is used mainly in limited speech by individual representatives of the population. Another group of specialists understand the term colloquialism on a wider scale, dividing it into several groups depending on the proximity or remoteness to the literary norm. Research methods. Currently, the study of colloquial speech is becoming one of the most important problems of modern linguistics. The study of colloquial speech at various linguistic levels is becoming increasingly important for a number of reasons. It becomes possible to collect and analyze material on the problems of colloquial words and expressions through the use of such methods of analysis as descriptive, systemic and structural, nominative-derivational, comparative-typological, statistical. Results and discussions. It is important to timely identify the features of the formation of colloquialisms and analyze new trends in terms of the lexical and semantic nature of colloquialisms in modern electronic and printed lexicographic sources, scientific works of foreign authors.