birdbrain

noun

1. (colloquial)Someone who is not intelligent.

   “That birdbrain just drove right through three rows of traffic cones and into the bushes.”

   “Comedienne Carol Channing, 29, admitted that a grave personal problem had grown out of her playing the role of birdbrained Lorelei Lee in Broadway’s Gentlemen Prefer Blondes. People seemed to be convinced that she is a birdbrain offstage, too: “I won't say that people actually think I’m just two steps removed from outright idiocy, but they do seem to have adopted a protective attitude towards me...””