Bohm, it great to have a personal definition of soemthing, but the actual word/term means NOT believing in God/Gods.
You can sugar coat it any way you like, but it means NOT believing in "theis" ie: God or Gods.
If you harbour a belief that there is SOME POSSIBILITY of their being a "god", then you really can't be an atheist in the true sense of the word.
Granted I would think that the vast majority of Atheist would fall into the category of "the jury is not back yet" or " I need more convincing to believe but I am keeping an open mind".