Set expressions in modern English
A set expression, being the object of study, is a group of words, not less than two in number (but typically more), characterized by a single, indivisible, specialized meaning, thus each set expression can be viewed as a separate unit and can be equalized to a separate word.
The number of set expressions in any modern language with a developed history is great, and the nature of such units is immansly versatile. It is a common mistake to think, that a set expression characterizes by its presence colloquial speech and always carries in its semantic structure an element of connotation, like emotionality, evaluation, intentisty, etc. – this is a mistake. Set expressions may be stylistically neutral, they may be terms, though many of them are highly colloqual by nature. Typical examples in English are in front of, not for the world, a red letter day, to sleep like a log, it goes without saying, etc.
The starting problem with set expressions is that of naming them, and the options here are phraseology, phraseological units and idioms. However, the terms phraseology and phraseological unit are recognized in Russian linguistics. Besides, the term phraseology also denotes the branch of linguistics that studies the word groups of the said kind.
We should also bear in mind that the phraseological section of the national vocabularly was best of all studied in Russian linguistics, while such units are still very poorly and non-systematically learnt in modern western linguistics. The linguists of the western countries mostly apply the tern idioms to both groups of words and single word units. This is done on the ground of the figurative meaning, manifested in this or that unit.
In reality all these units are highly heterogeneous (variative). Here we may find:
a) expressive colloquialisms (to know the ropes (знать все ходы/выходы));
b) demotivated units (tit for tat (зуб за зуб));
c) terminology (direct object, blank verse, Adam’s apple);
d) polytical cliché (a summit meeting, Cold War);
e) emotionally neutral combinations (to give up, a lot of, a great deal of, to be looking forward to, as well as).
Set expressions should not be confused with free phrases and semi-fixed combinations.
A free phrase easily permits substitution of any of its elements without the resuling semantic change in the remaining elements, e.g. to go early can be changed to to go late, and the meaning of go doesn’t change, as well as we can change it to to start early, etc.
In semi-fixed combinations substitutes also exist, but their boundaries are fixed by the semantic properties of words, which may be used for substitution. For example, there exists a pattern, consisting of the word to go + preposition + noun without an article, e.g. to go to school. The said pattern, however, is only used with the nouns of place, e.g. to go to hospital, to go to court, to go to lecture, to go to market, etc.
In this respect, if any substitution of elements within a phrase is restricted to only a few synonyms for one element, which is normally not basic, or such substitution is impossible, that is if the elements of the phrase are always the same, that is are used in the same grammar form with the same word order, making a fixed context, then the group is a set expression.
The naming set expression, unlike phraseological unit or phraseological entity or idiom, is most neutral, hence most acceptable. This way we do not change anything in such structures as first night, to gild the pill (подсластить горькую пилюлю), on the other hand, calf love (детская любовь, юношеское увлечение), to and fro.