Synonyms for Retard (same or very similar meaning)
WordNet sense 1 (a person of subnormal intelligence):
changeling, cretin, imbecile, moron, half-witWordNet sense 2 (slow the growth or development of):
check, delayWordNet sense 3 (lose velocity; move more slowly):
decelerate, slow, slow upFrom the ODE community, based on WordNetadd/edit