The article focuses on the phenomenon of inter-part-of-speech antonymy and types of inter-part-of-speech antonymic oppositions typical of the English language and represented in authentic sources, in particular, fiction books of English-speaking writers. The paper analyzes cognitive foundation and linguistic sources of the oppositions in question, describes their range within each part of speech as well as contextual means of intensifying the oppositional contrast. The authors argue that the traditional point of view, according to which only words belonging to one and the same part of speech can form antonymic oppositions, is insufficient and claims that inter-part-of-speech antonymy has a semantical and grammatical nature as it is based on the ability of the language to give different categorial form to the same fragments of reality. The results of the research show that practically all works of fiction include inter-part-of-speech antonymic oppositions, which thus can be treated as a regular language phenomenon. The paper contributes to the theory of parts of speech, giving additional information about their interaction and its cognitive basis. It also enriches the theory of antonymy, proposing a wide approach to antonymic oppositions.