[Hodar]

While no longer considered Poltically Correct, it is absolutly an accurate description.

re·tard   
verb (used with object)
1. to make slow; delay the development or progress of (an action, process, etc.); hinder or impede.
verb (used without object)
2. to be delayed.

It's only very recently that this has been considered "insulting" or "derogatory" when it is a completely acceptable term. I'm not very PC, as I consider the PC Police to be more concerned about "thought control" than anything else. Mentally Retardation means that an individual is mentally slow or delayed. It doesn't mean they cannot learn, that they are not meaningful individuals. Words mean things - the PC police have shaped this term to mean something that it doesn't.

[JLLH]

Very well said. Many parents of children with Down’s Syndrome and other birth defects object vehemently to this term, but it does need to be understood for what it is. But this is what happens when vocabulary and etymology are no longer studied in school. There is no comprehension of root meanings anymore.

[skinkinthegrass]

concise/short/to the point.
PC (political correctness) ism; is thought control..
"it's the hallmark of liberal government school (NEA)"