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

Sources of Homonymy
Divergence of word meaning is the process observed in those cases when different meanings of the same word deviate so far from each other that they come to be regarded as two separate units.
/flauə/
flower from Lat. flos, florem, OFr.flour, flor > ME flour ‘flower’;
flour ‘powder made by crushing grain’. Used from 13c. in the sense of the ‘finest part’ of meal (cf. Fr. fleur de farine ‘flower of flour’). Spelled flower until flour became the accepted form c. 1830 to end confusion.
toast, n
-a slice of bread made brown and crisp by cooking in high temperature, from O.Fr. toster ‘to brown with heat’ (12c.);
-a call to drink to someone's health (1700), originally referring to the beautiful or popular woman whose health is proposed and drunk, from the use of spiced toast to flavor drink.
Convergent sound development is the process which leads to the phonetic coincidence of two (or more) words that were phonetically distinct at an earlier date, e.g.
-OE ic and eaʒe > ModE I and eye /ai /;
-the disappearance of the sound k before n, e.g. knight – night, knot –not;
-the convergence of the ME ā, ai, ei, e.g. fair – fare, pale – pail, wait – weight;
-race 1 and race 2 from Old Norse rās 'running' and MFr from It razza 'ethnic group';
- Fr. mèche ‘wick’ (фитиль), OE meche ‘partner’ > match 1 ‘сірник’, match 2 ‘a relationship, a partnership’, as in matchmaker.
Loss of inflections, e.g. OE lufu (n) and lufian (v) - ModE love; OE sunne and sunu – ModE sun and son.
Conversion which serves the creation of grammatical homonyms, e.g. iron, n. - iron, v.; work, n. - to work, v.
Shortening, e.g. fan, n. ‘an enthusiastic admirer of some kind of sport or of an actor, singer, etc.’ (a clipping from fanatic) – fan, n. ‘an implement for waving li8ghtly to produce a cool current of air’.
Sound-imitation, e.g. bang, n. ‘a loud, sudden, explosive noise’ – bang, n. ‘a fringe of hair combed over the forehead’; mew, n. ‘the sound a cat makes’ – mew, n. ‘a seagull’.