ethics

Here the word usually follows the name of a field: business ethics, medical ethics, journalistic ethics. Each names the code expected of people in that line of work. In this sense it takes a plural verb, as in medical ethics require. That sets it apart from the academic discipline, where ethics is treated as a single subject and takes a singular verb.

Behind every sense here is Greek êthos, "character, moral nature," which reached English through Late Latin ethica, Middle French ethique and Middle English etik. That root still colors the broad sense. Ethics is close to morality, but it leans toward character: a person's ethics are the principles their conduct reveals. That is why personal ethics can be called strong, the way a character can.

A philosopher's name for the discipline, also called moral philosophy. It asks how moral judgments are justified and what makes conduct right or wrong. Consequentialism, deontology and virtue ethics answer those questions differently. Deontology is sometimes offered as a synonym for the whole field, but strictly it names the duty-based theory, one approach within ethics rather than ethics itself.

Two nouns share this spelling. One is the mass noun of the broad "morality" sense. This one simply means more than one ethic, each a set of principles belonging to a particular culture, group or individual. A useful test: if the singular an ethic would fit the sentence, it is this plural, as in the competing ethics of two movements.