a. A set of principles of right conduct.
b. A theory or a system of moral values: "An ethic of service is at war with a craving for gain" (Gregg Easterbrook).
2. ethics (used with a sing. verb) The study of the general nature of morals and of the specific moral choices to be made by a person; moral philosophy.
3. ethics (used with a sing. or pl. verb) The rules or standards governing the conduct of a person or the members of a profession: medical ethics.
[Middle English ethik, from Old French ethique (from Late Latin ēthica, from Greek ēthika, ethics) and from Latin ēthicē (from Greek ēthikē), both from Greek ēthikos, ethical, from ēthos, character; see s(w)e- in the Appendix of Indo-European roots.]
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