Polysemy in the Cognitive Perspective

Polysemy is a prevailing phenomenon in languages.It means that a word has many differences in meanings but coherences in semantic network.Different meanings of a word make up a semantic category,in which each member is not of the equal importance.Some are prototypes,while others are not.Polysemy lies in the semantic extension from its prototype to periphery by the cognitive devices of metonymy and metaphor.Semantic extension is also the product of categorization and conceptualization on the basis of image schemas.