A person who is strong enough that they have come to their own conclusions about religion. These people do not just jump on the bandwagon and believe what everybody else tells them. Many people think that atheists are ungodly and sinners, but are in truth just normal people who have their own beliefs. Saying that an atheist is a sinner or an ungodly person is racism as well and is no better than saying that Jewish people or Islamic people are evil. And it is a common stereotype to say that all atheists are pompous or know-it-alls, they are just normal people who have come up with their own original thoughts on life.
Yes, I am an atheist. That does not mean that I am an immoral person, it just means that I have different beliefs than the general public.
And I wouldn't be going off on this tangent, but some of the definitions I have seen for this word are unfair and extremely biased.