Where does “адъ” come from?

адъ (Church Slavonic) comes from Ancient Greek ᾍδης, from Proto-Indo-European n̥-, from Proto-Indo-European ne — not.

Ancestry of “адъ”, step by step

StepLanguageWordMeaning
1Ancient GreekᾍδηςHades (Greek god)
2Proto-Indo-Europeann̥-not, un-
3Proto-Indo-Europeannenot

Words derived from “адъ”

Every word from Proto-Indo-European ne →Every word from Proto-Indo-European n̥- →Every word from Ancient Greek ᾍδης →