Introduction. The article deals with the emotional concept ANXIETY. The topicality of the research is determined by the contemporary linguistics’ interest towards emotional concepts and a human’s inner world. Purpose: the aim of the research is revealing concept features of the concept ANXIETY and analysing its structure, as well as its cognitive and discursive peculiarities. Materials and methods. The research is based on the analysis of monolingual English dictionaries, works of Russian and overseas linguists and practical English grammar books. The theoretical perspective of the paper is the critical epistemic discourse analysis. The paper considers mental representation of the concept ANXIETY. Results, discussion. A concept in the given paper is defined as a complex structure with its features involving several subconcepts. The concept ANXIETY includes the subconcepts ‘emotional state’ and ‘volition’. Each subconcept has its own concept features, correlates with a particular prototypical situation, has different conceptual ties and is represented in different structures with verbals. The essence of diffusiveness of the given concept is that depending on the communication aim a speaker focuses on a particular concept feature, thus realising a certain subconcept. The concept ANXIETY is described as a diffusive one based on syncretism. The research posits the status of subconcepts as units of human mental activity which constitute syncretism of the concept ANXIETY. Conclusion. The concept ANXIETY is syncretic in nature and includes two subconcepts “emotional state” and “volition”. Subconcepts are full units of speech and mental activity explicating certain structures of knowledge.