Good (also “well”) is a fundamental concept in ethics, morality, philosophy, religion, and other fields that concern human behavior. The word’s specific meaning and etymology vary greatly among cultures and traditions, but its basic role in ethical reasoning is generally the same: It identifies something that ought to be preferred to something else. In some contexts, it may be contrasted with evil.

The concept of good has been central to many philosophical schools and philosophies, including Aristotelianism, Deontological Ethics, and Utilitarianism. For example, Aristotle argued that to live the good life means excelling at what makes humans distinct from animals: rational thought, which he characterized as the characteristic activity of the human soul. The idea that a good life lies in the exercise of reason has been an essential element of ethics ever since.

In the early modern period, the ideas of Jeremy Bentham and G. E. Moore brought an analytical focus to the study of goodness. Both argued that there are certain things that are simply not good, and that our knowledge of what these are can be derived from a comparison with our experience. Their analysis marked an important shift toward conceptual analysis in moral philosophy, and influenced later work by philosophers such as Franz Brentano.

It is generally accepted that “good” and “well” are synonymous, although some old notions persist that only good should be used to describe virtue and well should be used only as an adverb after feeling. This probably stems from the fact that the English adverbs “feeling” and “well” have the same etymological origin: Old English godd, presumably from the root of god (“affection, pity”) and -od (“to fatten”). In Spanish, both good and well can be predicated of an adjective, and both can be used to express satisfaction, pleasure, or agreement: “I feel very good!”; “nunca lo hemos hecho tan bien!”

Having the qualities that are desirable or appropriate for a particular purpose: a good secretary; a good winter coat; a good investment; a good book. Also used to mean kind, generous, or approving: She is such a good friend; He does the right thing most of the time; It’s a good job he’s working on this project. The term is also used in casual speech to refer to someone who is obedient, well-behaved, or polite. In some languages, the word is used to denote physical health and fitness: I am feeling good; I am in good condition. In other cases, it is a figurative or descriptive adjective: She is good-looking. She is a good seamstress. A good ice cream is made from a quality milk and cream. Goods are manufactured and sold, such as a good leather car seat or a good quality of flour.