thisness
This term is primarily used in metaphysical and scholastic philosophical discourse to describe the irreducible individuality of an object. It focuses on the specific quality that makes a thing "this" particular thing and not any other, even if another object shares every single identical property. It is a highly technical term and is rarely encountered in casual conversation or general literature.
Because it describes an abstract, singular quality of identity, the word is treated as an uncountable noun. It does not refer to a collection of traits but to a singular state of being, meaning it does not take a plural form in standard philosophical usage.
Meanings
The quality of being a particular, unique individual or thing, as opposed to a general category or type.
The philosopher examined the thisness of the object to understand its singular identity.
In scholastic philosophy, the property of an object that makes it a specific individual, also known as haecceity.
The concept of thisness allows for the distinction between two identical twins in a metaphysical sense.