"Every word instantly becomes a concept precisely insofar as it is not supposed to serve as a reminder of the unique and entirely individual original experience to which it owes its origin; but rather, a word becomes a concept insofar as it simultaneously has to fit countless more or less similar cases -- which means, purely and simply, cases which are never equal and thus altogether unequal. Every concept arises from the equation of unequal things. Just as it is certain that one leaf is never totally the same as another, so it is certain that the concept "leaf" is formed by arbitrarily discarding these individual differences and by forgetting the distinguishing aspects."

Also theEncyclopædia Britannica has all the definitions you are discussing. It is strange though to see how people start arguing about the real meaning of atheism, just as people discuss what interpretation of the Bible is correct. Seems not religion is to blame for all the conflict it is involved in, but the need to argue and be right that is inherent in most humans. South Park are incredibly spot on with their atheism episode.

"The first thing Fascists usually try to do is silencing the opposition."