The article highlights the peculiarities of the lexical composition of business English, which is the main tool of business discourse in a modern multicultural society. The peculiarities of modern business discourse in comparison with the established norms of business communication are noted. The set expressions, clichés, and terminological expressions are accompanied by the use of professional jargon in oral business speech. It has been found that the lexical composition of business English is represented by simple words, compound words, abbreviations, and phrasal words. The semantic composition of business English is represented by both common words and professional terms. Words that have more than one meaning, as well as noun phrases, are widely used. The peculiarities of using business English in various fields, including management, marketing, advertising, etc. are considered. The ability of individual words and phrases to acquire a different professional meaning in the context of a particular field of business activity of entrepreneurs and companies is highlighted. The features of using business English as a professional jargon in the context of business discourse are analyzed. Examples of business English terminology are presented, in particular, terminology that is widely used by representatives of business circles in Ukraine. Examples of phrasal verbs and abbreviations used in business discourse are given. The peculiarities of using noun phrases in written business discourse are clarified, and examples of such phrases are given. It is noted that business discourse is characterized by a combination of business communication and extralinguistic context. Expressive words, idiomatic expressions, and metaphors, have become widely used in modern business discourse. Professional jargon as a layer of specialized vocabulary is used by representatives of one professional field with professionally limited vocabulary for the purpose of professional communication.