Where does “endosymbiosis” come from?

endosymbiosis (English) comes from English symbiosis, from Ancient Greek συμβίωσις, from Ancient Greek συμβιόω, from Ancient Greek σῠν-, from Ancient Greek σύν, from Proto-Hellenic *ksún — beside, with.

endosymbiosis (English): The condition of living within the body or cells...

Definitions

The condition of living within the body or cells...

Ancestry of “endosymbiosis”, step by step

Step	Language	Word	Meaning
1	English	symbiosis	A relationship of mutual benefit, especially...
2	Ancient Greek	συμβίωσις	a living together, companionship
3	Ancient Greek	συμβιόω	to live together
4	Ancient Greek	σῠν-	together; with, together
5	Ancient Greek	σύν	beside, with
6	Proto-Hellenic	*ksún	beside, with

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