Great word! Seems to me polyonymy has several aspects: it includes words for the same thing in different languages (cat, chat, gato, gatto, 猫); names referring to different aspects of the same thing (Venus, morning star, evening star); nicknames (Elvis the Pelvis, The King, The Memphis Flash); and allonyms, different words for the same thing in the same language (Caribbean English: eggplant, antrover, aubergine, baigan... {see allonym for details}. It does not include synonyms that refer to different but similar things (automobile, sedan, jalopy).
Great word! Seems to me polyonymy has several aspects: it includes words for the same thing in different languages (cat, chat, gato, gatto, 猫); names referring to different aspects of the same thing (Venus, morning star, evening star); nicknames (Elvis the Pelvis, The King, The Memphis Flash); and allonyms, different words for the same thing in the same language (Caribbean English: eggplant, antrover, aubergine, baigan... {see allonym for details}. It does not include synonyms that refer to different but similar things (automobile, sedan, jalopy).
Contrast with polysemy, which is one word for many things.
Use of many names for same thing; use of polynomial term or name.