As I use the term, it is “An Emergent Property of any social or individual system in motion defined by:
Self Pity/Resentment
Perceptual rigidity
A lack of the ability to directly control internal states, making that person or group entirely vulnerable to whatever happens outside. This in turn leads to a need for power.
This basic complex, of course, leads to hatred, to the rationalization, as needed, of actions taken to gain power; and quite often to the full rejection of any conceptions of shared humanity–outside, perhaps, of a small group.
Take the Iranian Mullahs. They are evil. They beat women that dress inappropriately, in their view. In so doing, they are operating from a very ridgid system of thought, and rejecting as relevant in any way the humanity and feelings of those women.
Undergirding the enterprise is a constantly stirred up resentment of Israel. One would think that if only Israel were destroyed, then paradise itself would ensue. This is a stupid and childlike idea, but it is one that is emotionally effective with the disenfranchised and uneducated.
I think this basic thought pattern is close to the truth.
Someone said to me that hate and fear are related. I think the connection is in that last aspect of the definition. Weak people fear change, since they doubt their ability to cope with it. This leads to a fear of change. This can, in turn, lead to a fear of any person or group who does things differently, since the public display of nonconformity could lead–such people fear–to change. Historically, this has both enabled and encouraged the conquest of differing cultures. First, you get their stuff, which is sufficient reason for the non-fearful; but second, you gain control of their lives, and no longer have to coutenance difference.
Islam was perhaps the first system of thought whose conquests were based exclusively on the elimination of cultural difference. Prior to them, most conquests were just for booty and land, and cultural conditioned imposed solely for bureaucratic efficiency. After the Muslims set the example, though, you did see similiar things in the New World, particularly the parts upon which the Spanish afflicted themselves.
Is such conquest evil? Yes, I think it is. Does that make religion evil? No. Islam spread throughout Central Asia without conquest. Buddhism, of course, went from India to Japan without a single shot fired.
In all this my logic is simple: if I define Goodness as the Emergent Property of the interactions with matter of the rejection-of-self-pity, perseverance, and Perceptual movement/Breathing, then Evil would be the opposite. They are self pitiers, quitters, and dogmatists or indifferent outright to higher perception.