flat earther

Noun

flat-earther (plural flat-earthers)

1. A person who believes or advocates the claim that the planet Earth is flat.
   • His commitment to remaining a flat-earther seems to be strengthened by counterarguments rather than weakened by them.

   Synonyms:

   flat-earthist, platygaean, platygaeanist, flattard, flerf

   Antonyms:

   globe-earther, sphericist, globehead, glober, globetard

2. (broadly, derogatory, figuratively) A person who believes or advocates an outlandish, discredited theory; a person who refuses to acknowledge the truth despite overwhelming evidence.
   • Global warming is settled, unless you are a flat earther or an energy company apologist.2008, Bob Sweere, "Voice of the Day: Global warming? Yes," News-Leader.com (Missouri), 16 Jun. (retrieved 1 July 2008)