LOON

I. noun Etymology: Middle English loun Date: 15th century lout , idler, boy , 3. a crazy person, simpleton , II. noun Etymology: of Scandinavian origin; akin to Old Norse lōmr ~ Date: 1634 any of several large birds (genus Gavia of the family Gaviidae) of Holarctic regions that feed on fish by diving and have their legs placed far back under the body for optimal locomotion underwater