In scholastic logic, differentia is one of the predicables; it is that part of a definition which is predicable in a given genus only of the definiendum; or the corresponding "metaphysical part" of the object. In the original, logical sense, a differentia is a concept — the notion of "differentia" is a second-order concept, or a "second intention", in the scholastic nomenclature. In the scholastic theory it is a kind of essential predicate — a predicate that belongs to its subjects de re necessarily. It is distinguished against the species by expressing the (specific) essence of the object only partially and against the genus by expressing the determining rather than the determined part of the essence.