Where does “syneruptively” come from?

syneruptively (English) comes from English syneruptive, from English syn, from English synonym, from Middle English sinonyme, from Latin synōnymum, from Ancient Greek συνώνυμος, from Ancient Greek σῠν-, from Ancient Greek σύν — beside, with.

syneruptively (English): In a syneruptive manner; occurring during the time of a volcanic eruption

Definitions

In a syneruptive manner; occurring during the time of a volcanic eruption

Ancestry of “syneruptively”, step by step

Step	Language	Word	Meaning
1	English	syneruptive	At the time of an eruption
2	English	syn	That has a torsion angle between 0° and 90°
3	English	synonym	A word whose meaning is the same as that of...
4	Middle English	sinonyme	—
5	Latin	synōnymum	synonym
6	Ancient Greek	συνώνυμος	Having the same name; Having only one meaning:...
7	Ancient Greek	σῠν-	together; with, together
8	Ancient Greek	σύν	beside, with
9	Proto-Hellenic	*ksún	beside, with

Every word from Proto-Hellenic *ksún →Every word from Ancient Greek σῠν- →Every word from Ancient Greek σύν →