There is psycholinguistic description of the lexeme heart as a component of the semantic group «Internal human organs» is providing in this article. The associative fields of the lexeme heart were formed on the basis of a free associative experiment. This associative experiment was conducted in two groups of respondents: the doctors, the group of students of a medical university, and students of the humanitarian faculties, who doesn’t have medical education. The specificities of the psycholinguistic significance were detected this lexeme in ordinary and professional language consciousness when associative fields, their core and periphery were comparing. The psycholinguistic significance of this lexeme in the two groups is different. The basic meanings, peripheral fields do not match. People who work in medical sphere gave the larger terminological medical vocabulary. It shows the professional awareness of this lexeme by specialists. Psycholinguistic meanings are compared with a generalized lexicographic description. The lexicographic meaning of the lexeme of the heart is wider than the psycholinguistic meaning during the approaches of convergence of the core of the semanthem in the vocabulary descriptions and the results of the experiment. The conclusion was made on the data about the features of the awareness of the lexeme of heart by ordinary and professional language consciousness.