spatterdash noun 1verb 1forms 3 noun1 •A cement-based slurry applied to a wall in order to improve adhesion of the render.A spatterdash treatment consisting of a cement:sand slurry may be used over the surface of these bricks to provide a mechanical key for rendering. — 1972 verb1 •To apply spatterdash to. formsspatterdashed · spatterdashing · spatterdashes