Hyslop gives the following excellent explanation of the Logical Definition, which as he states is the proper meaning of the term in Logic. He states:
"The rules which regulate Logical Definition are as follows:
1. A definition should state the essential attributes of the species defined.
2. A definition must not contain the name of word defined. Otherwise the definition is called a circulus in definiendo.
3. The definition must be exactly equivalent to the species defined.
4. A definition should not be expressed in obscure, figurative, or ambiguous language.
5. A definition must not be negative when it can be affirmative."