Archenemies are individuals or groups that have a deep-seated hatred for each other. Some synonyms for this word include rivals, foes, adversaries, antagonists, enemies, and opponents. These words describe a relationship between entities that are in constant opposition to each other, each trying to gain some advantage over the other. Other synonyms that can be used to describe this type of relationship include nemesis, antithesis, and hostile parties. These words reflect the idea of a continuous struggle between the entities involved, a struggle that often results in one trying to undermine the other. Regardless of the word used, the relationship between archenemies is always characterized by intense conflict.