Page "Erebus" Paragraph 2

The perceived meaning of Erebus is " darkness "; the first recorded instance of it was " place of darkness between earth and Hades ".

Hebrew ע ֶ ר ֶ ב ( ˤerev ) ' sunset, evening ' is sometimes cited as a source.

However, an Indo-European origin, at least for the name Ἔρεβος itself, is likelier