Synonyms of retarded

1 Syllable

slow, dim, dull, weak

2 Syllables

dummy, numbskull, simple, dumbbell, tardy, backward, stupid, gorked, dumbo, dopey, touched, sappy, yo-yo, pinhead, dumdum, tardier

3 Syllables

deferred, birdbrained, slow-witted, half-baked, retardo, subnormal, dim-witted, moronic, half-witted, opaque, remanded

4 Syllables

lamebrained, imbecile, defective, exceptional, feeble-minded, simple-minded, feebleminded

5 Syllables

underachieving