blithering (?.)

• absolute
• arrested
• babbling
• backward
• blasted
• blessed
• burbling
• crackbrained
• cracked
• crazy
• cretinistic
• cretinous
• dithering
• downright
• driveling
• drooling
• gross
• half-baked
• half-witted
• idiotic
• imbecile
• imbecilic
• maundering
• mentally defective
• mentally deficient
• mentally handicapped
• mentally retarded
• mongoloid
• moronic
• not all there
• out-and-out
• outright
• positive
• rank
• retarded
• simple
• simpleminded
• simpletonian
• slobbering
• subnormal