- ξύν (xún)
Homeric and Early Attic ξύν (xún) and Mycenaean ku-su- are its supposed early form. If not, with difficulty ( -υ- < *-o- is expected, but -σ- < *-s- and -σ- < *-ξ- are not), from Proto-Indo-European *som-, from *sem-, it might be a composition of this and one other element.
σῠ́ν • (sún) (invokes dative)
- In compounds it has similar applications, including completeness.
- συν- (sun-)