Pronunciation: (nem'u-sis), [key]
—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.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.