a person who does not accept or is out of touch with the realities/ beliefs of modern times;

one who blatantly dismisses/ disagrees with common knowledge or scientific findings.
Joe doesn't even believe the planet is round, or that we landed on the moon... he's a flat earther.
by G-Money12321 November 10, 2013
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An imbecile who was dropped on their head as a baby multiple times or divorced people who want to die
Yo that bitch is a flat earther. She tried to talk to me yesterday and I think I lost a brain cell
by Mesa big boy February 18, 2019
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One who believes in the theory of flat earths, perhaps as a result of having either a flat head or flat testicles.
Two flat-earther astronauts go into space.

"Look dude, we're orbiting a blue pancake!"
"Holy fuck! That's a funny ball-shaped pancake!"
by masterblaster01 January 17, 2018
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An utter moron who thinks that the Earth is flat. It is often difficult to sway them into thinking that the Earth is actually round. They often make YouTube videos about their 'proof' that the Earth is flat, which is often debunked by people that know Science.

NOTE: Despite what facts you state, they will refuse to believe you and say 'You've been converted.' or 'NASA is lying to you.'
Person 1: "Hey, look at that guy, he's a flat earther!"
Person 2: "Yeah, what a bafoon."
by barney is a sexy boi July 14, 2020
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Someone who thinks earth is a disk; Another definition is a mentally challenged person
The Karen down the street is a flat earther
by Yeeterskertt January 5, 2021
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A separate line of the genus homo sapiens (Humans) who believe that earth is flat. They lack in comprehension and learning skills seeing they believe earth is flat which is of course WRONG.
Random people in the internet: Earth is actually flat, get your facts right.
Me: Hahahahaha, flat earther are stupid
by deathlol November 15, 2017
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a fucking dumbass who fucking got fucked up in the head,hitting his head so many damn times on a brick as a child and always getting fucked up on pills as a child
guy1:the earth is flat
guy2:shut the fuck up you flat earther you degenerate fuck
by fire pro YT November 20, 2018
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