Accidental (from Latin accidens, accidentis) - in philosophy, this is a term denoting a random, insignificant feature or property of an object or phenomenon.
Accidental properties are contrasted with essential, inherent properties. For example, for a person, the display properties are eye color, height, weight, etc. And the essential property of a person is his rationality.
Accidental properties do not express the nature of a thing, its essence. They are random and can change without affecting the essence of the subject. Accidental properties are not obligatory, unlike essential properties.
The concept of “accidental” was widely used in medieval scholastic philosophy to distinguish between essence and appearance. In modern European philosophy, this term is used less frequently, but retains its basic meaning of an accidental, unimportant property.