Idiom - is a combination of linguistic units, the meaning of which does not coincide with the meaning of its constituent elements. This discrepancy may be a consequence of a change in the meaning of elements within the whole. There are intralingual and interlingual idioms. The latter are characterized by the impossibility of “literal” translation. Lexical idiom is a non-free combination of words (a type of phraseological units), characterized by a unity of meaning that cannot be derived from lexical components; it has the functional characteristics of a word as a nominative unit of language and is reproduced as a “ready-made” unit of language. Idioms have a wide variety of structures and combinations, mostly uninflected and often illogical, and may not follow the basic rules of grammar.