[loon] n [ME loun] (15c) 1: lout, idler
2. chiefly Scot: boy 3 a: a crazy person b: simpleton
[2]loon n [of Scand origin; akin to ON lomr loon] (1634): any of several large birds (genus Gavia) of Holarctic regions that feed on fish by diving and have their legs placed far back under the body for optimal locomotion underwater