The rules of correct definition are derived from the process of
concept-formation. The units of a concept were differentiated—by means of a
distinguishing characteristic(s)—from other existents possessing a
commensurable characteristic, a Conceptual Common Denominator. A definition
follows the same principle: it specifies the distinguishing characteristic(s)
of the units, and indicates the category of existents from which they were
differentiated.
The distinguishing characteristic(s) of the units becomes the differentia of
the concept’s definition; the existents possessing a Conceptual Common
Denominator become the genus.