Where does “πλαγία” come from?

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

Ancestry of “πλαγία”, 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

Every word from Proto-Indo-European -yós →Every word from Ancient Greek -ῐος →Every word from Ancient Greek πλάγιος →