It seems your dictionary was written by a theist, mine says "one who does not believe in gods or deity's", that is the definition I accept. I suggest you buy another one.

I totally agree that any definition of an atheist which just says they are someone who denies the existence of a god is far too narrow (& probably defined by a theist!) but not all dictionaries define an atheist that way if you read several entries.

To narrowly define an atheist as someone who denies the existence of a god is like saying all Nigerians are Africans therefore all Africans are Nigerians! OK maybe some atheists deny the existence of a god (I simply say there's no good reason to believe god claims but maybe there are LOTS of them seeing as they are ALL invisible L.O.L!)

It's a pathetic attempt to shift the burden of evidence from the claimant to the skeptic & is so culturally instilled into the public's consciousness by the church & schools & the media etc. that it's very very hard to point out that atheists simply find god claims implausible END OF STORY! If people STILL want to insist that atheists are actually deniers of a god that can obviously be true too BUT they still fit into the wider definition of people unconvinced by god claims don't they?

At that point people often muddy the waters even more by introducing the definition of an agnostic because agnostics don't know if there's a god or not but that's just a red herring. Agnosticism is about knowledge - or rather a lack or it where as atheism is about belief or rather a lack of it. END OF STORY.

Personally I tend not identify as an atheist simply because so many people don't 'get' this simple nuance & some of the people who don't are atheists themselves so God help us! (L.O.L!) I just say I'm a skeptic & don't believe any extraordinary claims lacking extraordinary evidence & that there's no reliable evidence at all for any gods. If people have a problem with that the burden of evidence is entirely on THEIR shoulders if they disagree that there's no good reason to think a god exists & they then have all their work cut out for them. - Can they give a good reason to think that there is one? NO. Not without assuming a lot & that's where I have fun picking their claims apart & showing just how ludicrous their opinions really are which really isn't difficult on close examination.