The Word of the Day is nemesis, defined as a formidable foe or enemy. As a proper noun, Nemesis is the Greek goddess of vengeance. The definition illustrates its common usage with an example of a championship opponent. The entry also provides a real-world example from a review of the character Skeletor. Historically, Nemesis was a Greek deity who dispensed both rewards and punishments. She was believed to enact vengeance not always immediately but sometimes over generations. In English, the word initially meant someone delivering just retribution. However, contemporary usage often focuses on animosity rather than justice. The core concept remains an opponent who is very difficult to overcome. This difficulty stems from the deep-seated nature of the opposition.