Where does “καθώς” come from?

καθώς (Ancient Greek) comes from Ancient Greek κατά, from Ancient Greek καταστερίζω, from Ancient Greek ἀστήρ, from Proto-Hellenic astḗr, from Proto-Indo-European h₂stḗr, from Proto-Indo-European h₂eHs- — to be/become dry; to burn, to glow; hearth.

Ancestry of “καθώς”, step by step

καθώς traces back through two separate lines of ancestry.

via Ancient Greek κατά

StepLanguageWordMeaning
1Ancient Greekκατά
2Ancient Greekκαταστερίζωto place among the stars; I put among the stars
3Ancient Greekἀστήρa celestial body; illustrious person; starfish
4Proto-Hellenicastḗrstar
5Proto-Indo-Europeanh₂stḗrstar
6Proto-Indo-Europeanh₂eHs-to be/become dry; to burn, to glow; hearth

via Ancient Greek ὡς

StepLanguageWordMeaning
1Ancient Greekὡςthe introduction to similes; to qualify a general...
2Ancient Greek-ωςAdded to the stem of adjectives or pronouns to...
3Proto-Indo-European-ósCreates agent nouns from verb stems, denoting...
Every word from Proto-Indo-European h₂eHs-Every word from Proto-Indo-European h₂stḗrEvery word from Proto-Hellenic astḗr