The article attempts to determine the nature of meanings in the semantic space of the lexicon by revealing the content of metaphors. A three-level classification of metaphors is presented within the scope of the article. Itsmain criterion is the degree of difficultiesin their compre-hension. The metaphors are arranged according to the principles of fluent and crystalized intelligence. A semantic structure of a word is viewed as a multi-level configuration of meanings. It is fixed by a dominant invariant meaning. The analysis of the English substantive “a leg” is presented. We have developed a new approach to the phenomena under consideration called the invariant-component method. As a result, the obtained semantic metaphorical clusters have lead to the lexical invariant definition. The latter is viewed as a set of basic dominant components that form the semantic core of a polysemous word. The results of the study led to the conclusion that lexical invariants make it possible to successfully decode metaphors of the first basic level according to our classification.