Source : Webster's Revised Unabridged Dictionary (1913)

Addle-brain \Ad"dle-brain`\, Addle-head \Ad"dle-head`\,
Addle-pate \Ad"dle-pate\, n.
   A foolish or dull-witted fellow. [Colloq.]

Source : WordNet®

addle-head
     n : a person with confused ideas; incapable of serious thought
         [syn: {addlehead}, {loon}, {birdbrain}]