The word polysemy means plurality of meanings. It exists only in the language, not in speech. A word which has more than one meaning is called polysemantic.
There are two processes of the semantic development of a word: radiation and concatenation. In cases of radiation the primary meaning stands in the centre and the secondary meanings proceed out of it like rays. Each secondary meaning can be traced to the primary meaning, e.g. face (the front part of the human head -
the primary meaning; the front part of a building, the front part of a watch, the front part of a playing card; expression of the face, outward appearance - secondary meanings).
In cases of concatenation secondary meanings of a word develop like a chain, e.g. crust – 1. hard outer part of bread, 2. hard part of anything (a pie, a cake), 3. harder layer over soft snow, 4. sullen gloomy person, 5. impudence. Here the last meanings have nothing to do with primary ones. In such cases homonyms appeare in the language. This phenomenon is called the split of polysemy.
