Being listed in a dictionary has nothing to do with something being true or existing in reality.
Here a few words that are listed in dictionaries:
"False Beliefs: a misconception resulting from incorrect reasoning."
"FALSE BELIEF: has a wide range of potential definitions mostly dependent on the application to real-life. For example, in an psychological application, false beliefs are internal cognitive representations which have no basis in reality."
"Leprechaun: a mischievous elf of Irish folklore usually believed to reveal the hiding place of treasure if caught."
Actually it's quite disturbing to watch people pretend that "false beliefs" are real beliefs in reality; in order to just cover for the shear inadequacy of their own worldview. But what can I do when people like you are willing to embrace their unbelief (atheism) as a worldview, rather than something that has at least a possibility to be true in reality.