That which is unique or particular to a mathematical object.

- Synonym for attribute, characteristic, or quality, according to the mathematical context in which this term is used.
- A mathematical object is often defined by a set of properties.

### Examples

- A square is a quadrilateral in which the four sides are isometric and the four angles are right angles. The isometry of the sides and the isometry of the angles are characteristic properties of a square.
- A quadrilateral is a four-sided polygon. The fact of having four sides is a defining property of a quadrilateral, a property that distinguishes it within the class of polygons.