in Homer, etc., the place of darkness between Earth and Hades, from Latin Erebus, from Greek Erebos, which is of unknown origin, perhaps from Semitic (compare Hebrew erebh "sunset, evening"), or from PIE *regw-es- "darkness" (cognates: Sanskrit rajas "the atmosphere, thick air, mist, darkness;" Gothic rikwis "darkness"). Used figuratively of darkness from 1590s.