We might divide definitions into four kinds. Let us look at them one by one.
But how do we know what the correct meaning of a term is? Many people think that a dictionary is an authoritative guide to reportive definitions. This is actually a misconception, for various reasons.
First, many words in the language are difficult, if not impossible to define. This includes for example color words which we learn from examples. A dictionary might explain "red" as the color of ripe tomatoes, but obviously this is not what "red" means. "Red" does not mean blue even if all tomatoes suddenly were to become blue when they ripe. Explaining 'red' as 'a certain shade of colour' is of course not enough to distinguish the colour red from other different colours.
Also, the main aim of a general dictionary is often to give enough indication of the main usage of a word so that a speaker can use the word adequately in everyday life. Because of the limitation of space the definitions might not capture adequately the exact meanings of words. For example, the Pocket Oxford Dictionary of Current English defines "religion" as "belief in a superhuman controlling power." Suppose a scientist discovers that there are evil but superhuman aliens on Mars who created us and control our destiny. The scientist would then believe in the existence of a superhuman controlling power. But if this scientist does not worship or submit to these beings, surely this does not mean she has a religion in the usual sense of the term.
Finally, many technical words, such as "microwave", "hyper-inflation", and "a priori" are used in rather specialized ways. The entries in a general language dictionary might not be accurate enough when it comes to such terms. In such cases you should consult a special dictionary for the particular discipline in question.
As an exercise, evaluate the following entries from The Pocket Oxford Dictionary of Current English as reportive definitions.
What about this entry from the Merriam-Webster Online Dictionary?
- Cat : Small soft-furred four-legged domesticated animal.
- Magazine : Illustrated periodical publication containing articles, stories, etc. [Hint]
- Impress : Affect or influence deeply.
- Cloud : Visible mass of condensed watery vapour floating high above the ground.
- Swim : Propel the body through water with limbs, fins, or tail. [Hint]
SUGAR : A sweet crystallizable material that consists wholly or essentially of sucrose, is colorless or white when pure tending to brown when less refined, is obtained commercially from sugarcane or sugar beet and less extensively from sorghum, maples, and palms, and is important as a source of dietary carbohydrate and as a sweetener and preservative of other foods.
Or consider a situation where two people are arguing whether animals such as birds or apes possess language. To resolve this dispute, we need to be more precise as to what is meant by "language". If by "language" we refer to any system of communication, then obviously birds and other animals do make use of languages. On the other hand, "language" might be used in a different sense, requiring a combinatorial syntax and semantics, allowing a user of the language to communicate information about non-existent objects or situations remote in time and space from the location of discourse. Used in such a way, the communication system of some animals might not qualify as a language. This example illustrates the use of precising definitions to resolve disputes that involve some key concepts whose meanings might not be clear enough.
In giving a stipulative definition, since we are introducing a new meaning, the question of whether the definition is too broad or too narrow does not arise. But it is important that the definien should avoid circularity, inconsistency and obscurity.
M02.7 Exercises
Do not believe in anything simply because you have heard it. Do not believe in anything simply because it is spoken and rumored by many. Do not believe in anything simply because it is found written in your religious books. Do not believe in anything merely on the authority of your teachers and elders.

Buddha