A definition describes the basis of integration of a specific concept. It describes the essential nature of the concept. It differentiates all other particulars from those included under the concept.

A concept has a genus and a differentia. The role of the definition is to describe both.

A genus is the category of particulars from which the concept draws on. Coffee tables, for instance, have the genus tables. Coffee tables are a subset of tables. They share the same characteristics of tables, although they have more specific requirements as well. The genus acts to eliminate all particulars that don't fit under its own definition. It also acts to describe what the remaining particulars have in common. The basis for its own integration. Tables are a type of furniture that have four legs, and objects are placed on it for temporarily.

The differentia acts to distinguish the particulars encompassed by the new concept from the remaining particulars subsumed under the genus. The coffee tables are a subset of tables. They differ from other tables by their use and size. They are smaller, and are used to place coffee, magazines, etc., on. The differentia is that which makes it different from the rest of the genus.

An explicit definition provides a clearer understanding of a concept. It allows a more complex manipulation and use of the concept. It also allows communication of what the concept is.