. | 1. | something that a person cannot conquer, achieve, etc.: The performance test proved to be my nemesis. |
| 2. | an opponent or rival whom a person cannot best or overcome. |
| 3. | (initial capital letter ) Classical Mythology. the goddess of divine retribution. |
| 4. | an agent or act of retribution or punishment. |
In classical mythology, the Greek goddess of vengeance.
Note: By extension, a “nemesis” is an avenger. One's nemesis is that which will bring on one's destruction or downfall.