No. It is exactly what they say they are. Just matter. That there is nothing beyond matter. That everything happened on accident. That there is no purpose to any of this.
I disagree with all of it by the way.
From Merriam Webster dictionary:
"
atheist
noun
athe·ist | \ˈā-thē-ist
\
Definition of atheist
: a person who does not believe in the existence of a god or any gods
: one who subscribes to or advocates
atheism"
That is the definition of "atheist". No where in that definition does it claim that all atheists believe everything originates from the material world.
If you wish to create your own definition, feel free to do so. I don't need a new definition.