The word nemesisses is a plural form of nemesis, which means an archenemy or a rival. There are several synonyms for nemesisses like adversary, antagonist, opponent, foe, rival, challenger, competitor, detractor, and enemy. Adversary is someone who opposes you in a struggle or a contest. Antagonist is the one who stands in the way of your goal or objective. Opponent is someone who competes with you in a game or sport. A foe is an enemy that is hostile towards you. Rival is someone who competes with you for the same thing. Challenger is someone who poses a challenge to you. Competitor is someone who competes against you in business or in a market. Detractor is someone who speaks negatively about you or criticizes you. Lastly, the enemy is a person who actively tries to harm you.