AbstractCarrying out the research task related to the study of semantic layers of different levels, ideal object revealing regardless of material substances, definition of the most significant, essential, and general semantic and mental properties, qualities and mechanisms of consciousness and basing on the invariant theory we introduced the concept of lexical invariant. It is interpreted by us as an aggregate of the most significant universal semantic components which are intuitively defined in the course of phenomenological reduction and are unchanged in the stream of meanings variation composing the semantic formula of a word or phrase