impenetrable
im.pen.e.tra.ble \(')im-'pen-*-tr*-b*l\ \-ble-\ aj [ME impenetrabel, fr. MF impenetrable, fr. L impenetrabilis,]fr. in- + penetrabilis penetrable 1a: incapable of being penetrated or pierced 1b: inaccessible to knowledge, reason, or sympathy : IMPERVIOUS 2: incapable of being comprehended : INSCRUTABLE 3: having the property of impenetrability - im.pen.e.tra.ble.ness n