Noah Webster's Dictionary (n.) An unbeatable opponent; a source of harm; the goddess of retribution; hence, retributive justice personified; divine vengeance.

Multi-Version Concordance Nemesis (1 Occurrence) Acts 28:4 And when the barbarians saw the beast hanging from his hand, they said to one another, This man is certainly a murderer, whom, though saved out of the sea, Nemesis has not allowed to live. (DBY)