(r)densely, thicklyin a concentrated manner“old houses are often so densely packed that perhaps three or four have to be demolished for every new one built”, “a thickly populated area”
(r)thicklywith thickness; in a thick manner“spread 1/4 lb softened margarine or cooking fat fairly thickly all over the surface”, “we were visiting a small, thickly walled and lovely town with straggling outskirt”