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

Extra-linguistic causes of semantic changes:
-historical, e.g. a pen ‘any instrument for writing’ < Lat. penna ‘a feather of a bird’; supper ‘the last meal of the day’ < Fr. souper < PIE *sup ‘to drink in sips’;
-social, e.g. a live wire ‘one carrying electric current’ > ‘a person of intense energy’, a feed-back ‘the return of a sample of the output of a system’ > ‘response’, to spark off in chain reaction, a launching pad;
-psychological, e.g. a don ‘a university teacher, a leader, a master’ > ‘the head of Mafia family or other group involved in organised crime’, bikini.
Linguistic Causes of Semantic Change
ellipsis is the omittance of one of the components in a word-group; the meaning is transferred to the other component, e.g. a presale view > a presale; to study works by Ch. Dickens > to study Dickens;
differentiation of synonyms, i.e. a gradual change of the meanings of synonyms which develop different semantic structures, e.g. autumn – harvest, a deer – a beast – an animal;
fixed context results from synonymic differentiation when one of the synonyms becomes to be restricted in use to a number of set expressions and compound words, e.g. meat originally ‘food’ (mincemeat, nutmeat, sweetmeat, meat and drink) > ‘edible flesh’;
linguistic analogy occurs when one of the members of a synonymic set acquires a new meaning and the other members of this set change their menaings in the same way, e.g. to snack – to bite.
Types of Semantic Change (by H. Hirt)
Changes in the denotative component of meaning:
generalisation (broadening, extension) is the widening of a word’s range of meanings, e.g. a fellow ‘a partner or shareholder of any kind’ > ‘a man; a person in the same group’; ready ‘prepared for a ride’ > ‘prepared for anything’; rich ‘powerful’ > ‘wealthy’ etc.;