1. A characteristic or quality that belongs exclusively or distinctively to a person or thing; a peculiar or distinctive attribute.
Usage: formal; chiefly philosophical or theological
2. In logic and metaphysics, a property that is proper to a thing but not part of its essential definition.
Usage: technical; philosophy

Examples

• Rationality is considered a proprium of human beings.
• The ability to laugh is sometimes cited as a proprium of humanity.
• In medieval philosophy, the proprium was distinguished from both the essence and accidental properties.
• Each species has its own proprium that sets it apart from others.
• The proprium of a triangle is that the sum of its angles equals 180 degrees.