Superlative form of stupid: most stupid.(adjective)
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Use "stupidest" in a sentence
"Willoughby, who also was as close-minded to outsiders as MacArthur, vied “for the title of stupidest intelligence chief of World War II,” one military historian has written."
"Had it all been just so that I could be called the stupidest man on earth, and accused of being on crack?"
"The MST must be among the most irrational, scatterbrained, and just plain stupidest taxes in the world."