Each definition includes three elements: the term to be defined, the genus, and the differentia; but these are not necessarily arranged in the order named.
EXERCISE
Select the three elements (the term to be defined, the genus, and the differentia) in each of the following:—
1. A polygon of three sides is called a triangle.
2. A square is an equilateral rectangle.
3. A rectangle whose sides are equal is a square.
4. Description is that form of discourse which aims to present a picture.
5. The characters composing written words are called letters.
6. The olfactory nerves are the first pair of cranial nerves.
7. Person is that modification of a noun or pronoun which denotes the speaker, the person spoken to, or the person or things spoken of.