Special Olympics and other groups have started a campaign to raise awareness to the usage of the word retard or retarded and the demeaning negativity it can convey to those who have various types of disabilities. Years ago, it was an official diagnosis. Recently however, the word has taken on a more general term used to describe someone who is uncool, stupid or just a plain loser. Here is the link to this article:
http://news.health.com/2013/03/06/one-word-you-need-to-stop-saying-heres-why/.