A mode or standard of personal behavior based on moral or ethical principles is defined as what?

The term that best fits the definition of a mode or standard of personal behavior based on moral or ethical principles is "conduct." Conduct refers to how an individual behaves in various situations, especially regarding adherence to moral and ethical rules. It encapsulates the idea of personal behavior shaped by moral understanding, guiding how one acts in both personal and professional contexts.

While "ethics" pertains to the overarching principles and theories that categorize what is right and wrong, it does not specifically refer to individual behavior on a day-to-day basis. "Discipline" generally relates to training or self-control rather than directly to a standard of behavior. "Moral standard" emphasizes the benchmarks for behavior but is more of a concept or ideal rather than a description of an individual's actual behavior. Thus, "conduct" aligns precisely with the definition given in the question.