Nemesis (in Greek, Νέμεσις), also called Rhamnousia/Rhamnusia ("the goddess of Rhamnous"), at her sanctuary at Rhamnous, north of Marathon, in the Greek mythology was the spirit of divine retribution against those who succumb to hubris, vengeful fate personified as a remorseless goddess. The name Nemesis is related to the Greek word νείμειν, meaning "to give what is due". The Romans equated one aspect of Greek Nemesis, which might be interpreted as "indignation at unmerited advantage", as Invidia (Aronoff 2003).
Nemesis is now used as a term used to describe one's worst enemy, normally someone or something that is the exact opposite of oneself but is also somehow similar. For example, white could be considered the nemesis of black. Professor Moriarty is freqently described as the nemesis of Sherlock Holmes.

Gained 2 pounds on this one..