[{"Bold_text": "noun", "List Items": ["Nautical.a vertical blade at the stern of a vessel that can be turned horizontally to change the vessel's direction when in motion.", "Aeronautics.a movable control surface attached to a vertical stabilizer, located at the rear of an airplane and used, along with the ailerons, to turn the airplane.", "any means of or device for governing, directing, or guiding a course, as a leader or principle:His ideas provided a rudder for the new company."]}]