Superlative form of foolish: most foolish.(adjective)
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Use "foolishest" in a sentence
"My best is like a five-finger exercise compared with the foolishest thing she ripples off."
"I could be content that we might procreate like trees, without conjunction, or that there were any way to perpetuate the world without this trivial and vulgar way of coition: it is the foolishest act a wise man commits in all his life, nor is there anything that will more deject his cooled imagination, when he shall consider what an odd and unworthy piece of folly he hath committed."
"Woman, he declares, is the "crooked piece of man," and man has no greater misfortune than that he must commune with her to reproduce: it is "the foolishest act a wise man commits in all his life.""