retard

延缓、阻碍、使减缓正式

Cold weather can retard the growth of these young plants.

寒冷的天气会延缓这些幼苗的生长。

拖延、使落后正式

A lack of funding has retarded progress on the new bridge.

资金不足使新桥的工程进度严重落后。

智障、白痴贬义、侮辱性用语

Calling someone a retard is deeply offensive and should be avoided.

骂别人智障是极为侮辱人的说法，应该避免。