Definition

It clarifies the way in which a word or phrase is being used in a given context and will often be the usage which people or the applicable specialist users of the term agree that the term should mean, but may also be a statement of the standard meaning of the word or phrase.

A good definition should be clearer and better understood than the word or phrase it defines.

Definitions should avoid circularity, for example, defining the word square simply as an “equilateral rectangle” may not be particularly helpful for anyone unfamiliar with the term, and especially if when one looks up equilateral rectangle one is given a definition of: “a square shape”. Negative definitions, in isolation, are generally of little use: such as a human being defined as “something which is not a polar bear”.

A definition should focus on the essential elements which characterize and distinguish this thing from other things, especially similar or related things, for example, defining a human being as a “primate without a tail” would be a confusing and inadequate definition in so much as the word primate refers to members of the large-brained, dextrous mammalian order which includes anthropoids: humans, apes, and monkeys; and prosimians: lemur, loris, and shrews. Definitions should not be too broad – including things which are not what is being defined – or too narrow – excluding instances of the thing being defined.