Also found in: Idioms, Wikipedia.


One who stubbornly adheres to outmoded or discredited ideas.

[From the long-discredited belief that the earth is flat.]

flat′-earth′ adj.


informal a person who does not accept or is out of touch with the realities of modern life
References in periodicals archive ?
It worries me that instead of having a sensible conversation on just how much man is responsible for changing the climate, anyone who doesn't toe the man-the-planet-destroyer line is now barracked as a fool and a flat-Earther.
The 53-year-old is far from a flat-earther, and he's not likely to take over the late Ginger McCain's mantle as the defender of Aintree as was.
All bar a small, flat-earther minority agree that changes have to be made to freshen things up and welcome new people.