(uncountable) Recognition of the distinction between good and evil or between right and wrong; respect for and obedience to the rules of right conduct; the mental disposition or characteristic of behaving in a manner intended to produce morally good results.

(countable) A set of social rules, customs, traditions, beliefs, or practices which specify proper, acceptable forms of conduct.

(countable) A set of personal guiding principles for conduct or a general notion of how to behave, whether respectable or not.

(countable) A morality play.

(uncountable, rare) Moral philosophy, the branch of philosophy which studies the grounds and nature of rightness, wrongness, good, and evil.

(countable, rare) A particular theory concerning the grounds and nature of rightness, wrongness, good, and evil.