I can't understand how you can say that term "polysemy" isn't normally used... How do you call the words with more meanings (and the grammatical phenomenon), then? It's not "homography", apparently!
The terms homonym and polysemy describe words; the terms reduced forms, connected speech, known also as fast speech, describe an array of (connected) words:
Aha... Thanks, bianca ... What do you mean (when you say it must be a good joke if you understand it)? Why does it make no sense?
Do I understand the joke well?
1st speaker: My wife's gone to the West Indies.
2nd speaker: Jamaica? (Did you make her (... go there??) ?)
1st speaker : No, she went of her own accord. (No, she went voluntarily.)
Exactly! You got it!
Just like 'kangaroo', 'Jamaica' is a sound immitation word or onomatopeic.
The terms homonym and polysemy describe words; the terms reduced forms, connected speech, known also as fast speech, describe an array of (connected) words: