Branches of linguistics. Synchronic vs diachronic approaches to the language study. Lexicology – ‘the science of the word’

Collocability is an actual use of words in particular word-groups in communication.
Lexical valency is the aptness of a word to appear in various collocations, i.e. in combinations with other words. The lexical valency of correlated words in different languages is not identical. Both the E. plant and Ukr. рослина may be combined with a number of words denoting the place where the flowers are grown, e.g. garden plants, hot-house flowers, etc. (cf. Ukr. садові рослини, оранжерейні рослини, etc.). The English word, however, cannot enter into combination with the word room to denote plants growing in the rooms (cf. pot plants — кімнатні рослини).
The interrelation of lexical valency and polysemy:
-the restrictions of lexical valency of words may manifest themselves in the lexical meanings of the polysemantic members of word-groups, e.g. heavy, adj. in the meaning ‘rich and difficult to digest’ is combined with the words food, meals, supper, etc., but one cannot say *heavy cheese or *heavy sausage;
-different meanings of a word may be described through its lexical valency, e.g. the different meanings of heavy, adj. may be described through the word-groups heavy weight / book / table; heavy snow / storm / rain; heavy drinker / eater; heavy sleep / disappointment / sorrow; heavy industry / tanks, and so on.
From this point of view word-groups may be regarded as the characteristic minimal lexical sets that operate as distinguishing clues for each of the multiple meanings of the word.
Grammatical valency is the aptness of a word to appear in specific grammatical (or rather syntactic) structures. Its range is delimited by the part of speech the word belongs to. This is not to imply that grammatical valency of words belonging to the same part of speech is necessarily identical, e.g.
-the verbs suggest and propose can be followed by a noun (to propose or suggest a plan / a resolution); however, it is only propose that can be followed by the infinitive of a verb (to propose to do smth.);
-the adjectives clever and intelligent are seen to possess different grammatical valency as clever can be used in word-groups having the pattern: Adj. + Prep. at + Noun (clever at mathematics), whereas intelligent can never be found in exactly the same word-group pattern.
-The individual meanings of a polysemantic word may be described through its grammatical valency, e.g.
- keen + N as in keen sight ‘sharp’; keen + on + N as in keen on sports ‘fond of’; keen + V(inf) as in keen to know ‘eager’.
Lexical context determines lexically bound meaning; collocations with the polysemantic words are of primary importance, e.g. a dramatic change / increase / fall / improvement; dramatic events / scenery; dramatic society; a dramatic gesture.