Which term describes socially unacceptable actions such as murder and incest?

The term that best describes socially unacceptable actions such as murder and incest is "taboos." Taboos are strong prohibitions against certain behaviors based on societal beliefs and values, and they often evoke a strong emotional reaction. These actions are so socially unacceptable that they are often considered to be beyond the realm of acceptable conduct, leading to severe consequences or social ostracism for those who engage in them.

Norms relate to the rules and expectations by which a society guides the behavior of its members, but they encompass a broader range of behaviors that include both acceptable and unacceptable actions. Values are general beliefs about what is desirable or important in a society, while ethics pertain to moral principles that govern a person's behavior or conducting an activity. While norms, values, and ethics can influence perceptions of taboos, taboos specifically refer to those actions that are vehemently rejected by society at large, making them the correct term in this context.