Where does “plagio-” come from?

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

Ancestry of “plagio-”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	πλάγιος	placed sideways, slanting, aslant
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 “plagio-”

plagioclase
plagiocephaly
plagiotropic
plagiocephalic
plagioclimax
plagiopatagium
plagiostomy
plagioclasic
plagio-

Every word from Proto-Indo-European -yós →

plagio- — Etymology, Origin & Word History | Etymology Explorer