Where does “*antius” come from?

*antius (Proto-Romance) comes from Latin ante, from Ancient Greek κλίσις, from Ancient Greek -σῐς, from Ancient Greek -τις, from Proto-Indo-European -tis — Derives abstract/action nouns from verb roots.

Ancestry of “*antius”, step by step

Step	Language	Word	Meaning
1	Latin	ante	before, in front, forwards; before; before,...
2	Ancient Greek	κλίσις	bending, inclination; a lying down; a place for...
3	Ancient Greek	-σῐς	"suffix forming nouns"
4	Ancient Greek	-τις	retained after dentals
5	Proto-Indo-European	-tis	Derives abstract/action nouns from verb roots

Words derived from “*antius”

eigne
ainz
aisné
ainznez
ainçois
aisné
ainçois
aîné

Every word from Proto-Indo-European -tis →Every word from Ancient Greek -σῐς →Every word from Ancient Greek κλίσις →