One who lacks the most important organ, a brain. One who believes that the Earth is Flat, and that space doesn't exist and is just a 'dome' around the Earth and everything is a lie told by the government.
Guy 1: How do u feel about Flat Earthers?

Guy 2: I feel that all Flat Earthers should be sent up in a rocket, and ejected into space, so their last sight will be a Spherical Earth in Space.
by Sur7 January 25, 2019
One who is mentally retarded in the head, was dropped as a child and snorts crushed up panadol.
by FrogBoot February 10, 2018
Guy1: That guys a flat earther.
Guy2: You mean a dumb ass
by Skin Ne Penis February 22, 2018
Someone who not only believes the Earth is flat, but will also claim any argument against their theory is government propaganda.
I hear Bob is a Flat Earther. We should send Bob up into space so he can get a harsh dose of reality.
by Gatch Attack July 22, 2017
Idiots who are mentally retarted and think this earth is a peice of paper
Flat Earthers are mentally retarted
by Eazy-E Jr. October 18, 2018
A Flat Earther is a person who pursues the belief that the world is flat, and tries to discredit centuries of astronomical discovery and scientific advancement, based on a childlike limited understanding of science and religion. No amount of proof or evidence will convince a Flat Earther that the earth is round like a ball, because their brain lacks the capacity to understand this reality.
Because he is a Flat Earther, he believes that if you go up high enough in a balloon, you can see all of the continents at the same time, because he thinks the world is flat.
by Moving Forward March 7, 2018
A severe mental disorder where someone struggles with geometry and believes, as you can tell from the name, that the earth is, in fact, flat.
I spanked a Flat Earther for being dumb.
by BoxEarth November 13, 2018