Nouns

(n)idiot, imbecile, cretin, moron, changeling, half-wit, retarda person of subnormal intelligence

Verbs

(v)retardcause to move more slowly or operate at a slower rate“This drug will retard your heart rate”
(v)retardbe delayed
(v)check, retard, delayslow the growth or development of“The brain damage will retard the child's language development”
(v)decelerate, slow, slow down, slow up, retardlose velocity; move more slowly“The car decelerated”