Where does “Κυριακή” come from?

Κυριακή (Ancient Greek) comes from Ancient Greek ἡ Κυριακὴ ἡμέρα, from Ancient Greek κυριακή, from Ancient Greek Κυριακός, from Ancient Greek -ακός, from Ancient Greek -κός, from Proto-Indo-European -ḱos — -y, -ic.

Κυριακή (Ancient Greek): Sunday, Lord's Day

Definitions

Sunday, Lord's Day

Ancestry of “Κυριακή”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	ἡ Κυριακὴ ἡμέρα	the Lord's Day
2	Ancient Greek	κυριακή	nominative/vocative singular feminine of κῡριακός
3	Ancient Greek	Κυριακός	of the Lord
4	Ancient Greek	-ακός	-ic
5	Ancient Greek	-κός	forms adjectives with the sense of 'of or...
6	Proto-Indo-European	-ḱos	-y, -ic

Every word from Proto-Indo-European -ḱos →Every word from Ancient Greek -κός →Every word from Ancient Greek -ακός →