'Impasto' definitions:

Definition of 'impasto'

noun

Painting that applies the pigment thickly so that brush or palette knife marks are visible

From: GCIDE

Impasto \Im*pas"to\, n. [It. See Impaste.] (Paint.) The thickness of the layer or body of pigment applied by the painter to his canvas with especial reference to the juxtaposition of different colors and tints in forming a harmonious whole. --Fairholt. [1913 Webster]