(also called idiom), a word group with a fixed lexical composition and grammatical structure; its meaning, which is familiar to native speakers of the given language, is generally figurative and cannot be derived from the meanings of the phraseological unit’s component parts. The meanings of phraseological units are the result of the given language’s historical development.
There are several types of phraseological units, as follows. In phraseological concretions the literal and figurative meanings are totally unrelated, as in tochit’ liasy (“to whittle a piece of linden wood”; figuratively, “to chatter”) or sobaku s”est’ (“to know inside out”; literally, “to eat a dog”). Other phraseological units have a meaning that is derived from the meaning of the component parts, as in plyt’ po techeniiu (“to flow with the current”). Phraseological collocations include a word or words with a meaning that is both literal and figurative, as in glubokaia tishina (“profound silence”). Another type of phraseological unit is the idiomatic expression, a word group whose structure and meaning are fixed.
Other classifications of phraseological units acccording to type exist as well. They include classifications based on the restrictions in the selection of variable structural elements, those based on the fixed or variable composition of the word components, and those based on the degree to which the phraseological unit’s structure and components are fixed. The aggregate of phraseological units differing in terms of meaning and structure constitutes a language’s stock of idioms.