Толковый словарь английского языка Oxford English Reference - impenetrable

adj. 1 that cannot be penetrated. 2 inscrutable, unfathomable. 3 inaccessible to ideas, influences, etc. 4 Physics (of matter) having the property such that a body is incapable of occupying the same place as another body at the same time. Derivatives impenetrability n. impenetrableness n. impenetrably adv. Etymology: ME f. F imp{eacute}n{eacute}trable f. L impenetrabilis (as IN-(1), PENETRATE)