1. A system of moral principles.
2. The rules of conduct recognized in respect to a particular class of human actions or a particular group, culture, etc.: medical ethics; Christian ethics.
3. Moral principles, as of an individual: His ethics forbade betrayal of a confidence.
4. The branch of philosophy dealing with values relating to human conduct, with respect to the rightness and wrongness of certain actions and to the goodness and badness of the motives and ends of such actions.