retardation

1. N-UNCOUNT Retardation is the process of making something happen or develop more slowly, or the fact of being less well developed than other people or things of the same kind. 延遲; 減緩; 落後[正式] [usu supp N]

...other parents whose children had mental retardation. ...其他智障兒童的家長(zhǎng)。