THE THREE KINDS OF DEFINITIONS ILLUSTRATED AND COMPARED.
Etymological Definition of Trigon.
A trigon is a figure of three corners.
Descriptive:
A trigon is a figure which has three sides and three angles, the sum of the latter being equal to two right angles.
Logical:
A trigon is a polygon of three angles.
It is seen that an etymological definition is simply a root-word analysis. In the case of trigon, the prefix comes from the Greek, meaning three, while the root-word comes from the Greek meaning corner.
The descriptive definition of trigon names the properties, “three sides and three angles” (differentiæ) and the accident, “the sum of the angles of which equals two right angles.”
The logical definition of trigon simply states the proximate genus, “polygon,” and the differentia, “three angles.”