The Oxford English Dictionary lists "to not believe in; to have no faith in; to not credit" as a definition for "disbelieve." So, according to what is generally considered to be the most authoritative and well-respected dictionary on the English language ever produced, a person who does not believe in any gods, or has no faith in any gods, is an atheist.Yet stated in the past 6 posts which you overlooked, atheism IS NOT a lack of belief.
On a side note, it has always amused me how people who don't call themselves atheists insist on trying to tell people who do call themselves atheists what the word means.