n[C]
[Sense: 1; Date: 1600-1700; Origin: From a Scandinavian language.]
[Sense: 2; Date: 1600-1700; Origin: loun 'bad person' (15-19 centuries) (influenced by LOON1 (because of its wild sound) and by LOONY¹)]
a large North American bird that eats fish and that makes a long high sound
informal a silly or strange person - used humorously