A necessary condition of any semantic change is some connection, some association between the old meaning and new one. There are two kinds of association involved in various semantic changes – metaphor and metonymy. 

 Metaphor.

The word “metaphor” came from the Greek language metapherō (to carry over, to transfer) [– meta (between) and phero (to bear, to carry). A metaphor is a transfer of the meaning based on comparison and an association of similarity of two objects, phenomena. Metaphor can be based on different types of similarity:

 similarity of shape, e.g. head (of a cabbage), the neck of the bottle, teeth (of a saw, a comb);

 similarity of position, e.g. foot (of a page, of a mountain), head (of a chair, the procession);

 similarity of function, behaviour e.g. a lady-killer – a man who is attractive and successful with women and can fascinate them,

a whip (an offi cial in the British Parliament whose duty is to see that members were present at the voting);

 similarity of colour, e.g. orange, hazel, chestnut, the gilded youth, a sunny smile, black gold, black economy.

Many metaphors are based on parts of a human body, e.g. the leg of a table, an eye of a needle, arms and mouth of a river, head of an army. A special type of metaphor is when Proper names become common nouns, e.g. philistine – a mercenary person, vandals – destructive people, a Don Juan – a lover of many women, etc. When new words are needed in order to describe things that did not exist before, they are often created by means of metaphor. With the growth of computer technology, we need words to describe many new objects and activities – and most of these new words have been produced metaphorically. The metaphors that are used in computer language come from many different areas of life, e.g. surfi ng, net, home page, mailbox, mouse, virus, window.

Metonymy.

Metonymy is a transfer of the meaning on the basis of contiguity. It is a change of names between things that are known to be in some way and associating two referents, one of which can have resembles the other. There are different types of metonymy:

 the material of which an object is made may become the name of the object, e.g. a glass, boards, iron etc.;

 the name of the place may become the name of the people or of an object placed there, e.g. the House – members of Parliament,

Fleet Street – bourgeois press, the White House – the Administration of the USA, etc.;

 names of musical instruments may become names of musicians, e.g. the violinist, the saxophonist, the pianist, etc.;

 the name of some person may become a common noun, e.g. «boycott» was originally the name of an Irish family who were so much disliked by their neighbours that they did not mix with them, «sandwich» was named after Lord Sandwich who was a gambler. He did not want to interrupt his game and had his food brought to him while he was playing cards between two slices of bread not to soil his fi ngers;

 names of inventors very often become terms to denote things they invented, e.g. «watt» , «om», «rentgen» etc.;

 some geographical names can also become common nouns through metonymy, e.g. holland (linen fabrics), Brussels (a special kind of carpets), china (porcelain), astrachan (a sheep fur) etc.