A drawing or other representation of an object that could not exist in actual three-dimensional space, the best known examples being the Freemish crate, impossible trident, the Penrose triangle, and the staircase illusion. It is a misnomer, because what is impossible is not the figure but what it represents. Impossible figures feature strongly in the work of the Swedish artist Oscar Reutersvärd (1915–2001) and the Dutch artist Maurits C(ornelis) Escher (1898–1970). Also called an Escher figure or an undecidable figure. See also visual illusion. Compare ambiguous figure.