Adultery is defined as extramarital sex that is considered morally or socially unacceptable. As such, there are numerous synonyms for the word adultery that are often used to describe this type of behavior. Examples of synonyms for adultery include infidelity, cheating, unfaithfulness, betrayal, and affair. Other synonyms for adultery may describe specific types of extramarital activities or relationships, such as swinging, polyamory, open marriage, or having a mistress. Ultimately, the use of synonyms for adultery may vary based on personal beliefs, cultural norms, and the context in which the behavior is occurring.