The Collaborative International Dictionary of English v.0.48:
Addle-brained \Ad"dle-brained`\, Addle-headed \Ad"dle-head`ed\, Addle-pated \Ad"dle-pa`ted\, a. Dull-witted; stupid. "The addle-brained Oberstein." --Motley. [1913 Webster] Dull and addle-pated. --Dryden. [1913 Webster]