1. Large somewhat primitive fish-eating diving bird of the Northern Hemisphere having webbed feet placed far back; related to the grebes
   "The eerie call of a loon echoed across the misty lake";
   - diver
    
2. A worthless lazy fellow
   "His mother complained that he was becoming a loon, sleeping all day and doing nothing"
    
3. A person with confused ideas; incapable of serious thought
   "The old loon couldn't remember where he had parked his car";
   - addle-head [informal], addlehead, birdbrain

Sounds like:

Derived forms: loons

Type of: bum [N. Amer, informal], deadbeat [informal], do-nothing [informal], gaviiform seabird, idler, layabout [informal], loafer, misfit, shirker [informal], slacker [informal]

Part of: Gavia, genus Gavia

Encyclopedia: Loon, Iran