Where does “pelagius” come from?

pelagius (Latin) comes from Ancient Greek πελάγιος, from Ancient Greek -ῐος, from Proto-Indo-European -yós — Creates adjectives from noun or verb stems.

Ancestry of “pelagius”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	πελάγιος	of the sea
2	Ancient Greek	-ῐος	belonging to; of”, “belonging to”, “pertaining to
3	Proto-Indo-European	-yós	Creates adjectives from noun or verb stems

Words derived from “pelagius”

Pelagius
Pelagian
Semipelagian
Pelagianist
Paez
Páez
pailán
Paio
paiolo
Paez

Every word from Proto-Indo-European -yós →

pelagius — Etymology, Origin & Word History | Etymology Explorer