An ELT Glossary : Polysemy

• Definition : The relationship between words which have the same form and different but related meanings.

• Example :  Crane (the bird with a long vertical neck and pointed horizontal beak) and crane  (the construction mechanism that looks like the bird); branch (of a tree) and branch (of a bank, family or other organisation) - again, the meanings are related: an organigram of an organisation would resemble a tree.

• Polysemes should not be confused with homonyms which are words which, by chance have the same form, but have unrelated different meanings – eg bank (of a river) and bank (financial organisation); bear (animal) bear (tolerate).