skim coat noun 1skim-coat verb 1forms 4 noun1 •A thin layer of plaster, glue, plastic, or other substance applied over a surface in order to cover imperfections and make it smoother.A skim coat touches up small voids. — 2004 skim-coat verb1 •To apply a skim coat.You can skim-coat the piece with spackling comound, following the length of its grain and dragging the knife over the surface at a slight angle so that you fill in only the grain. — 1990 formsskim-coated · skim-coating · skim-coats · skim coats