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Polysemy, Metonymy and Metaphor

A brief comparison of polysemy, metonymy and metaphor.

A "ship" is a vehicle used to transport material across water. It is a noun, and is literal in its use.

"Ship" has become a verb, meaning "(to) transport". Because it shares its etymology with the noun "ship", it is a polyseme. Since it substitutes a word ("transport") that is part of the same domain, it is also a metonym. It is still within its domain, so it is not a metaphor.

When the noun version of "ship" leaves its domain and substitutes a vehicle in the domain of air or space, it becomes the metaphor "airship" or "spaceship". Since "ship's" figurative meaning shares its etymology with "ship's" literal meaning, it, too, is a polyseme. Since, as a metaphor, it is no longer in its original domain, it cannot be a metonym.

Here is an approximation of the difference between metonym, metaphor and polyseme: 

• A metonym is an introspective (inward looking) equation: one item within a domain replaces another in the same domain, as if equal.

• A metaphor is an extrospective (outward looking) equation: one item within a domain replaces another in a different domain, as if equal.

• A polyseme is a retrospective (backward looking) equation: one item has multiple meanings with equal etymologies.

All "ships" return to the same polysemous harbour...

Comments...?

Copyright J.D. Casnig, 2006