OPACITY

n. 1 opaqueness, darkness, murkiness, dimness, obscurity, impermeability, impenetrability The opacity of the lens increases automatically in the presence of sunlight 2 obscurity, density, impenetrability, unintelligibility, indefiniteness, vagueness, reconditeness, abstruseness, ambiguity, equivocation, mystification For centuries scientists were unable to penetrate the opacity of the question of what occurred when substances burned 3 stupidity, dullness, denseness, thickness, obtuseness A light finally dawned through the thick opacity of his brain