PHRASEOLOGICAL UNITS, FREE WORD GROUPS (PHRASES), COMPOUND WORDS.
Phraseological units occupy an intermediate position between free word combinations and compound words. On the one hand, they are combinations of words and lack external inseparability. On the other hand, they are semantically integral and function as words.
A free word combination does not exist in language as a ready-made unit: it is created in the process of speech, a big house (adj. + noun), to read books (verb + noun), on the table (prep. + noun), etc.
Its meaning is derived from the meanings of words that make it up. In speech language-units are combined according to the structural patterns of the English language.
The freedom we speak of is the freedom or choice of the lexical units to fit into a given structural pattern. We can say big house or small house or big man or big bag etc. The freedom here is relative depending upon logical factors (to read apples is illogical, a laughing triangle does not make sense logically, etc.) and linguistic factors (traditionally we say to do one’s job and not to make one’s job; grammatically adverbs do not combine with nouns or numerals with prepositions; stylistscally some words are incompatible).
A compound word is grammatically and semantically inseparable and exists in the language as a ready-made unit reproducible in speech (unless it is a «potential» word).
A phraseological unit is also reproduced in speech as a ready-made unit. There is no freedom in the choice of the component lexical units.
Its meaning may be described as idiomatic because the meaning of the whole is not equal to the sum of the meanings of words which compose it.
A phraseological unit functions as a single syntactic unit irrespective of the number of words of which it consists (e.g. to take in, to make up, to go to bed, are verb-equivalents and have the syntactical functions of verbs; best man, first night, red tape, black ball are noun-equivalents and have the syntactical functions of nouns).
Set expressions have sometimes been called «word equivalents», and it has been postulated by A.I. Smirnitsky that the vocabulary of a language consists of words and word equivalents (word-groups), similar to words in so far as they are not created in speech but introduced into the act of communication ready-made.
Thus, phraseological units are word-equivalents and as such are part of the vocabulary of the English language.
The boundaries between free combinations of words and phraseological units are not always clearly marked.
Phaseological units are primarily characterized by the contradiction which exists between the semantic integrity of the whole and the formal independence of its parts.
But this independence is formal because, owing to the loss of its semantic independence, an element of a phraseological unit cannot be regarded as a word of full value, of full standard nature.
The phraseological unit is a word-equivalent, its components may be regarded as morpheme equivalents.
To sum up, there are free combinations of words, compound words and word-equivalents (phraseological units) which occupy an intermediate position.
Word-equivalents are distinguished from free combinations of words by their semantic isolation. It follows, from this semantic isolation that the meaning of the whole dominates over and suppresses the meanings of the components of this word equivalent.
Thus we may say that although a word-equivalent retains formal identity with the syntactic pattern of a free combination of words it is semantically isolated and idiomatic.
Word-equivalents are distinguished from compound words by their formal structure which does not differ from free combinations and by their idiomatic character. The majority of compound words are not idiomatic.
Their main characteristic feature lies in their inseparability or structural cohesion, idiomatic character being a complementary feature. In contrast to compound nouns the idiomatic character of phraseological units is their chief distinguishing feature.