There are so many words seen as synonymous with evil, most are actually not.
Evil is (in my opinion) simply that which cancels out or restrains influences for wellbeing.
Acts can be of evil intent without simply being evil.
For example cruelty is an evil act but not all evil acts are cruel sometimes they can be seemingly pleasant, kind or beneficial, while ultimately benefiting only one or a few at a high expense to the many.

Evil is intentionally causing harm.

I like to do a little study, okay probably more than a little. I remember I so identified with a Ted Talk not to long ago on shame. Although I identified with shame and think most can. What I really Identified with when she spoke about the idea that if I could simply know as much as I can about a situation , knowledge surrounding an issue and understand it then My life would be so much better. The truth is thats a lie I tell myself. I am not saying knowledge isnt helpful but its only part of this practice called living. What I have found is that its usually less than half the issue. It's like a interesting statement i have come across in self help. Your never upset for the reason you think you are. Just like that a lot of times the problem you think your having isn't the real problem your having. its something your only scratching the surface and you want to put it in definite terms and it just doesnt always fit in a box like that. Its usually more like the great song from the Great Don Henley "Heart of the Matter" We go through life and get lost and Broken.

"The more I know, the less I understand. All the things I thought I knew, I'm learning again [uploadstars.com]

Sin and Evil were both archery terms In Aramaic Here it is in Simplest terms

Theres more to it, and Im not going to state people don't do things with malicious intent cause they do. I have personally dealt with person(s) with the clinical definition of personality disorders. It has been my experience in society that the word socio or psycho path or variations are thrown around a little lightly without being the actual clinical definition. We get hurt in life and we hurt others. Personally my weapon of choice was words. That was how I Intentionally hurt others, other times I was so lost in my issues and was so focused on me and trying to feel okay, get what i want that I thought would make me feel better. I was blind to my actions and how I was treating others. 12 step and recovery history, the 12 step meeting i went to was codependents anonymous, another issue was religion, especially in the 12 steps.

For the record, I define "evil" as the set of actions or the single action taken in a moment that is the most destructive to human life and/or the quality of human life (as defined within parameters delineated by the basic physiological needs for food, water, shelter, attention and sex) and the belief system which validates those actions.