FEEBLE

minded adj. stupid, dull(-witted), witless, moronic, idiotic, imbecilic, simple, slow (on the uptake), slow-witted, weak-minded, dim-witted, addle-pated, halfwitted, deficient, subnormal, mentally defective, retarded, attocerebral, Brit ESN (='educationally subnormal'), Colloq dumb, thick, soft in the head, boneheaded, empty-headed, vacant, Brit gormless, US exceptional: Why do you spend so much time with that feeble-minded twit?