Term: Rudder Image: [{"name":"images\/public\/dictionary\/Rudder_h3l4addy.jpg","usrName":"Rudder.jpg","size":5528,"type":"image\/jpeg","thumbnail":"images\/public\/dictionary\/thRudder_vp6xfr7x.jpg","thumbnail_type":"image\/jpeg","thumbnail_size":5528,"searchStr":"Rudder.jpg,!:sStrEnd"}] Definition: Underwater fin mounted below the hull near the stern that controls boat steering.