Change of meaning is one of the most important ways of enlarging the vocabulary of any language. Meanings change when people attach a new significance to a word.
Every language changes and develops constantly. There are external and internal causes of changes in word-meaning. External causes of this process are:
1) changes in social life of a community, resulting in the appearance of new words;
2) changes of things the names of which are retained;
3) terminological use of words by people of various professions, where words modify their meaning, acquire a new sense;
4) adaptation to special purposes: a) intensity of meaning; b) the desire to speak in gentle and favourable terms of some person, object, or event, which is ordinarily seen in a less pleasing light, i.e. the use of euphemisms (Rayevska, 1979: 130).
Change of meaning in various languages has been described, in books and monographs of many scholars, where we find logical and psychological classification of its types. the following types of change of meaning are distinguished: a) extension (generalization) of meaning; b) narrowing (specialization) of meaning; c) elevation (amelioration) of meaning; d) degradation (degeneration) of meaning.
Specialization is a gradual process when a word passes from a general sphere to some special sphere of communication.
Generalization is a process contrary to specializaton, in such cases the meaning of a word becomes more general in the course of time.
Metaphor is a transfer of the meaning on the basis of comparison. Herman Paul points out that metaphor can be based on different types of similarity: a) similarity of shape; b) similarity of position; c) similarity of function, behaviour; d) similarity of colour.
Metonymy is a transfer of the meaning on the basis of contiguity. There are different types of metonymy: a) the material of which an object is made may become the name of the object; b) the name of the place may become the name of the people or of an object placed there; c) names of musical instruments may become names of musicians; d) the name of some person may becom a common noun. e) names of inventors very often become terms to denote things they invented; f) some geographical names can also become common nouns through metonymy.
Elevation is a transfer of the meaning when it becomes better in the course of time.
Degradation is a transfer of the meaning when it becomes worse in the course of time.
Hyperbole is a transfer of the meaning when the speaker uses exaggeration.
Litote is a transfer of the meaning when the speaker expresses affirmative with the negative or vica versa.