Άδης

Etymology: From Ancient Greek Ἅιδης (Hāidēs), possibly from Proto-Indo-European *n̥-wid- ('unseen'). The name likely refers to the invisible nature of the underworld and its ruler. This etymology connects to the English word 'invisible' through the same root meaning 'to see.' The alpha-privative prefix (ἀ-) combined with the root related to seeing (ϝιδ-) literally means 'the unseen one' or 'the invisible one.'