Long answer: I do not. Well, at least not a clear, absolute definition of evil. There are only personal morals, socially accepted ethics, and the sacrifice of one or both for a self-serving purpose. People usually associate self-involvement with evil, but some of the most heinous acts in history have been carried out by people who thought they were completely, unquestionably in the right. What is "evil" to people willing to hurt others to serve their moral doctrine? Is there opinion on such a thing even valid since they're clearly out of touch with societal ethics? By that logic, "evil" is anything that is far out of line with accepted group ethics and rules/"common sense" laws. In many cases, though, this logic doesn't work. For example, a 2015 recent Gallup Historical Trends survey says that approximately 61% of Americans are in favor of the death penalty. It is very clearly a socially accepted view; however, I don't see how opposition to the death penalty could be seen as "evil" unless a person who opposes it has an ulterior motive (such as planning a murder and trying to avoid the death penalty), but then it is the associated action that is "evil," not the value itself. Still following this logic, it would be reasonable to say that "evil" is radical deviance from the ethical norm *with the intention to hurt others.
So now we look at various religious and cultural groups. I was raised into Christianity (although I don't associate myself with it anymore), so I'll use that as an example. According to the Bible as well as many Christians, several things are "evil" that do not cause harm to others. Rejection of the biblical God and sexual impurity are the two most obvious. The former is replicated in many religions, essentially labeling everyone as "evil" by various standards. The latter has been a hot debate topic for decades, and has both factual evidence and fluff on both sides. One might say that those who oppose things like same-sex marriage and sexual liberation of women are evil because they are trying to influence society (and inevitably hurt some people) to align it with their personal moral code, just as one might say that those who promote highly sexual and inappropriate behavior are evil for the same reason.
Short answer: Evil is whatever you believe it is, unless you're crazy or out of touch with reality.
The closest thing to "evil" that I can think of is a person who hurts others for the sole purpose of entertainment, but that is based on my personal values that may be very different from someone else's.