1) Addle-head 2) Doofus 3) Dumbo 4) Dummy 5) Incapable of serious thought 6) Loon 7) Misfit 8) Noodlehead 9) Pinhead 1) Addlehead 2) Ass 3) Bimbo 4) Boob 5) Dingbat 6) Dodo 7) Dope 8) Idiot 9) Loon 10) Moron 11) Nitwit 12) Simp 13) Stupe 14) Twit 
A birdbrain refers to a stupid person. Often it refers to a person with a short attention span. Birdbrain or bird brain may also refer to: ...
Birdbrain is slang for a silly, inane or frivolous person.
a stupid, foolish, or scatterbrained person.