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baffling problem, brain twister, Chinese puzzle, clincher, conclusive argument, crossword puzzle, crusher, crux, enigma, enigmatic question, finisher, jigsaw puzzle, knockdown argument, knot, knotty point, mind-boggler, mystery, nut to crack, perplexed qu
\Floor"er\, n. Anything that floors or upsets a person, as a blow that knocks him down; a conclusive answer or retort; a task that exceeds one's abilities. [Colloq.]