Where does “unsynonymous” come from?

unsynonymous (English) comes from English synonymous, from Latin synonymus, from Ancient Greek συνώνυμος, from Ancient Greek σῠν-, from Ancient Greek σύν, from Proto-Hellenic *ksún — beside, with.

Ancestry of “unsynonymous”, step by step

unsynonymous traces back through two separate lines of ancestry.

via English synonymous

StepLanguageWordMeaning
1Englishsynonymoushaving an identical meaning; having a similar...
2Latinsynonymus
3Ancient GreekσυνώνυμοςHaving the same name; Having only one meaning:...
4Ancient Greekσῠν-together; with, together
5Ancient Greekσύνbeside, with
6Proto-Hellenic*ksúnbeside, with

via English un

StepLanguageWordMeaning
1EnglishunOne
Every word from Proto-Hellenic *ksúnEvery word from Ancient Greek σῠν-Every word from Ancient Greek σύν