loon Meaning, Definition & Usage

  1. noun a worthless lazy fellow
  2. noun large somewhat primitive fish-eating diving bird of the northern hemisphere having webbed feet placed far back; related to the grebes
    diver.
  3. noun a person with confused ideas; incapable of serious thought
    birdbrain; addle-head; addlehead.

WordNet

Loon noun
Etymology
Scot. loun, lown, loon; akin to OD. loen a stupid man; prob. for an older lown, and akin to E. lame.
Definitions
  1. A sorry fellow; a worthless person; a rogue.
Loon noun
Etymology
For older loom, Icel. lmr; akin to Dan. & Sw. lom.
Definitions
  1. (Zoöl.) Any one of several aquatic, wed-footed, northern birds of the genus Urinator (formerly Colymbus), noted for their expertness in diving and swimming under water. The common loon, or great northern diver (Urinator imber, or Colymbus torquatus), and the red-throated loon or diver (U. septentrionalis), are the best known species. See Diver.

Webster 1913