After various types of information sent from outside are combined in our brains and adapted, after it, they become compound words. Adaptation in this form results in the formation of compound words based on both synonymity and antonymity by combining words with different meanings. The other part of compound words are made up of words that expressing opposite meanings. Man’s cognitive activity has made it possible to distinguish between the things that exist in nature and, in general, any concepts in certain features. It is as a result of this activity of the brain words have been formed that are opposite to each other in the language, and these words have been regrouped to form compound words. In cognitive linguistics, one of the components of compound words is considered to be the main one, and in general, it affects which part of speech the newly formed compound word is. In compound words, the first element takes a stress, but the second element defines a new class of compound words. The formation of compound words is closely related to conceptual factors. Mostly complex words are the result of the formation of a conceptual mixture. In this process, the elements of the two concepts are selected and “mixed” with a new, more complex concept. The article discusses the expression of compound lexical units’ components with parts of speech in the English and Azerbaijani languages, which are different system languages, and their cognitive features. Various scientific sources have been used in writing the article.