flat-earther

[flat-ur-ther]

noun

a person who adheres to the idea that the earth is flat.
a person who clings to an idea or theory that has long been proved wrong.

Origin of flat-earther

1930–35; flat earth + -er¹

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for flat-earther

flat-earther

noun

informal a person who does not accept or is out of touch with the realities of modern life

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012