“Sfumato: (it., evaporated) The soft gradation of light tones into dark ones, such that all sharply defined contours are eliminated. About light and shade in painting, Leonardo da Vinci wrote that they should blend imperceptibly,’without lines or borders, in the manner of smoke.’ Compare CHIAROSCURO.”
Excerpted from: Diamond, David G. The Bulfinch Pocket Dictionary of Art Terms. Boston: Little Brown, 1992.