Someone whose mother drank while pregnant, though it is also a possibility that they have suffered a blow to the head, causing mental retardation.
Person 1: Did you know that Jessica is a flat earther? Person 2: Yeah, her mom should have never had that one sip...
By ranocchio
A reminder that as much of a failure that you are, there is always someone more disappointing than you. (although you are currently on Urban Dictionary, so maybe not so much).
"You strike me as someone who would be a Flat Earther"
By younerd
A piece of junk that lacks common knowledge and is an overall fucking dumbass
Oh your a Flat Earther? you should be saying your a dumbass.
By wower321322
Someone who believes that the Earth is flat.
There goes a Flat Earther.
By Non-Biased-Commenter
Someone named Claudius
A child-like thinker named Claudius has below average IQ, and is a Flat Earther.
By RoundEarther