A condition resulting from some imperfection, which may be structural (constitutional) or functional.
Structural looks to the possession and integrity of being; functional to fitting and well-ordered action.
To possess beingln imperfection is the lot of all created natures; in this sense all created natures are evil, when considered in relation to God, Who is absolute perfection of being.
Integrity of being looks chiefly to the absence of any substantive or accidental defect of constitution.
Such integrity is wanting in congenital feeble-mindedness, in traumatic insanity, in the deformed, the malformed and the maimed.
Functional imperfection is found in non-traumatic insanity, in ignorance and error, in the diseased, the perverted, and in those who are anti-socially disposed.
It will be seen from this analysis of what is admittedly evil in fact, that evil is of its nature a negative entity-an absence, a want, a defect, a perversion-a denial of good.
Moral evil is properly a functional defect, a free and deliberate defection from a known standard of moral goodness.
In this proper sense it applies only to action, and is called sin.
In a wider sense it means any condition that tends to evoke sinful action.
New Catholic Dictionary