nemesis
//ˈnɛməsɪs//
Noun
nemesisSingular
nemesesPlural
1
A long-standing rival or archenemy who is difficult to defeat or overcome.
The chess champion finally faced his nemesis in the tournament finals.
2
A source of harm, ruin, or downfall that one cannot escape.
His gambling addiction became his nemesis, eventually costing him everything.
3
An agent or act of retribution or punishment.
His downfall was the nemesis for years of corruption.