Where does “synonymos” come from?

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

synonymos (Latin): synonymous

Definitions

Step	Language	Word	Meaning
1	Ancient Greek	συνώνυμος	Having the same name; Having only one meaning:...
2	Ancient Greek	σῠν-	together; with, together
3	Ancient Greek	σύν	beside, with
4	Proto-Hellenic	*ksún	beside, with