make (sth) slow or late 使（某物）放慢或迟缓: retard the mechanism, eg of a clock 使机械装置减速（如时钟的） * retard thespark, eg of an engine 使点火延迟（如发动机的）. 
slow the progress or development of (sb/sth); hinder 阻碍（某人[某事物]）的进步或发展; 妨碍: Lack of sun retards plant growth. 光照不足则植物生长缓慢.> retardation / 9ri:tB:5deIFn; 9ritBr`deFEn/ n [U]: mental retardation 智力迟钝.
retarded adj backward in physical or (esp) mental development 身体或（尤指）精神发育迟缓的; 智力迟钝 的: be severely (mentally) retarded （智力）发育极为迟缓.