Where does “στις” come from?

στις (Greek) comes from Ancient Greek εἰς, from Proto-Hellenic ens, from Proto-Indo-European h₁én — in.

Ancestry of “στις”, step by step

στις traces back through two separate lines of ancestry.

via Ancient Greek εἰς

StepLanguageWordMeaning
1Ancient Greekεἰςinto
2Proto-Hellenicens—
3Proto-Indo-Europeanh₁énin

via Ancient Greek τάς

StepLanguageWordMeaning
1Ancient Greekτάςfeminine accusative plural of ὁ; the
Every word from Proto-Indo-European h₁én →Every word from Proto-Hellenic ens →Every word from Ancient Greek εἰς →