exact
Exhaustively described.
A thing is “exact,” as Ross uses the term, if it is comprehensively and exhaustively described by our concept of it.
Material things, Ross warns, can never be comprehensively described by our conceptual descriptions of them. Our concepts will always be inadequate for such a purpose. No language, concept or even thought of a real thing can be “exact” or “entirely comprehended” in this sense. Why not? Because no set of concepts or even thoughts can fully capture the overflow necessities of a real thing. There will always be some aspect of the necessities that compose a thing which is hidden to us. That’s why Ross dubbed them “hidden necessities”: they “overflow” any concepts we might have (concoct) about them.
Exactness of Concepts VS. Bottomless Well of Overflow Necessities.
T&W: material things cannot be exact, that is, be entirely comprehended without overflow in conceptions or definitions. Material things overflow our conceptions. Their overflowing features are not merely their individuality and accidents, but also many of their natural necessities.
Formal objects, of course, can be “exact” (comprehensively described by their definitions), because they are their definitions.
There is nothing more to a tetrahedron than its definition within the formal system provides. There is more to a sugar cube than is contained in our conception of it, even more than our best science contains or will, no matter how comprehensive that becomes, because the de re necessary conditions spread out into the inaccessible.