Monumental Folly Share definition Flag A thoughtless action resulting in tragic consequence great in extent, or size. Mao Zedong's "Great Proletarian Cultural Revolution" was a monumental folly . Monumental Folly by ElliotMcvey November 15, 2020 0 0 Get merch Get the Monumental Folly mug. Buy Now — $32.95 See more merch