Pronunciation: (nem'u-sis),[key] —n., —pl.-sesPronunciation: (-sēz").[key] 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. (cap.) Class. Myth.the goddess of divine retribution.
4. an agent or act of retribution or punishment.