Where does “-eiz” come from?

-eiz (Old French) comes from Latin -icius, from Latin -icus, from Ancient Greek -ικός, from Ancient Greek -κός, from Proto-Indo-European -ḱos — -y, -ic.

Ancestry of “-eiz”, step by step

Step	Language	Word	Meaning
1	Latin	-icius	-itious
2	Latin	-icus	belonging to; derived from; of or pertaining to;...
3	Ancient Greek	-ικός	of or pertaining to, in the manner of; -ic
4	Ancient Greek	-κός	forms adjectives with the sense of 'of or...
5	Proto-Indo-European	-ḱos	-y, -ic

Words derived from “-eiz”

Every word from Proto-Indo-European -ḱos →Every word from Ancient Greek -ικός →Every word from Latin -icus →