Language is not liquid. Language is LEGOs (tm). If you use too few blocks you create a very rough form. To add detail you must add scale. So too with language, complex ideas tend to be poorly represented in sparse wording. Once more efficiency is the enemy of quality.
I am a staunch and unashamed atheist. And when I describe myself as an atheist I know exactly what I mean. But I've exchanged ideas with enough people who call themselves atheists to know that though they use the same word they may not mean the same specific thing.
And I've seldom exchanged ideas with theists (on points of contention) when I didn't find it necessary to clarify definitions and implications of words and phrases to avoid equivocation and general miscommunication. Again the words atheism and atheist are likely to create misconceptions. When I use these words I know I am probably seeding a conversation.
I like the term naturalist. But that can be confused with bird-watchers or nudists. I like the term humanist but it seems new-age-y, evasive and doesn't really get the point across. I like secularist but that is more of a political position. "Bright" is immodest. If there is a better word than "atheist" it may not be coined yet. It was super-naturalists who coined and wielded the word atheist. Would it not be poetic justice if they were undone by it?
One way to have the atheist conversation while avoiding the stigma is to balance the Socratic method with dismissals of ungrounded ideas. For some reason it is more acceptable to hold and share a perspective of non-belief as long as you don't seem to have an actual position. By "playing dumb" you can avoid a lot of labels and prejudice. By asking for explanations and details you can also un-stuff or avoid many strawman arguments.
English language and Western culture seem particularly unfavorable to non-super-naturalist. For instance we still say the Sun comes up. And though we know it is the Earth's rotation moving into view, we still think of it as the Sun coming up. Try to describe a situation wherein someone experiences random but favorable circumstances without referring to luck or providence. So too "atheist" carries culturally and historically ingrained stigmas similar to "pagan," "witch" and "devil worshiper."
But by shying away from this word we give it power. We would be foolish to allow "atheist" to become "the A word." Let us instead change the meaning, not by committee or decree, but by action and example. And when archaic stigmas are made moot by an overwhelming inability to stereotype a subset of society who share nothing in common but a lack of belief, what we are called will be equally arbitrary. Let the "non-religious" and "unaffiliated" look on us with admiration so that they too may call themselves what they really are: people find no merit in religious claims, aka: atheists.