polysemy

Polysemy is a linguistic phenomenon in which a single word form has multiple related meanings. The senses of a polysemous word share an underlying semantic field and are interpreted via context. Polysemy is widespread across languages and a key source of lexical ambiguity in discourse.

Polysemy is contrasted with homonymy, where relatedness is absent and the meanings share only form. For example, bank as a financial institution and bank as the riverbank are usually treated as homonyms rather than polysemes.

Polysemy often arises through metaphorical extension or metonymy: a foot becomes the base of a person and then a unit of length; a mouth is an opening in a body that can also denote openings in natural or man-made objects (mouth of a river, mouth of a bottle).

The word foot shows polysemy: foot (body part); foot of a mountain (base); foot (unit of length). The word mouth shows polysemy: mouth (oral cavity); mouth of a river or mouth of a bottle (openings).

Studying polysemy helps in lexicography, language learning, and NLP, where sense disambiguation is needed. Dictionaries typically list multiple related senses under a single lemma; computational resources like WordNet organize senses into synsets with semantic relations. Cross-linguistic polysemy is common and translations require selecting the appropriate sense.