1) Asinine 2) Brainless 3) Dense 4) Dumb 5) Foolish 6) Imbecile 7) Imbecilic 8) Inane 9) Moronic 10) Retarded 11) Silly 12) Stupid 1) Brainless 2) Deficient 3) Deficient in intelligence 4) Dense 5) Dim-witted 6) Dull 7) Feebleminded 8) Half-witted 9) Headless 10) Idiotic 11) Imbecile 12) Imbecilic 13) Indecisive 14) Lacking intelligence 15) Moronic 16) Not endowed with intelligence 17) Obtuse 18) Pathetic 19) Retarded 20) Slow 
[adj] - without much intelligence
adjective lacking intelligence; `a dull job with lazy and unintelligent co-workers`
deficient in intelligence; dull; stupid. · not endowed with intelligence.