Absolute: As a substantive, a being which is self-sufficient in its existence. As an adjective, that which exists (metaphysical sense), or is known (logical sense) without requiring to be connected with something else or with something already known; in this sense it is the same as unconditional and is the opposite of relative. ‘Absolutum est non dependens ab alio’ (In IV Metaph., l. 19)
Abstraction: an operation by which the intellect expresses to itself the essence of a thing whilst ignoring those determinations of it which make it such and such a particular thing. ‘Abstrahere speciem intelligibilem a phantasmatibus est considerare naturam speciem absque consideratione individualium principiorum quae per phantasmata repraesentantur.’ (ST, I, q. 85, a. 1 ad 1)
Accident: That which cannot exist and which cannot be conceived of except as dependent upon some presupposed being. An ONTOLOGICAL ACCIDENT is a reality whose natural mode of existing is in another being. ‘Accidens est res cui debetur esse in alio’ (In IV Sent., dist. 12, q. 1, a. 1, sol. 1, ad 2). Ontological accidents are either CONTINGENT or NECESSARY. A LOGICAL ACCIDENT, one of the predicables, is the contingent mode in which a predicate is related to a subject. ‘Accidens est quod contingit eidem inesse et non inesse praeter subjecti corruptionem’ (Sum. Log., T. I, c. viii).