Whether we like it or not, "retarded" has become a distasteful word to use. At one time, it simply meant "delayed" or "late in learning," innocent enough. But the behavior associated with using the word became ugly, and so the language use followed. It even became politicized, with words like "libtard," in a deliberate attempt to insult and denigrate people on the left side of the spectrum. I think "cretin" used to be a clinical term too. It will be interesting to see how current language evolves. But for the moment, my opinion is that a nurse or doctor who chooses to use this word shows a lack of understanding of verbal boundaries, empathy, and professionalism. The popular belief is that the word is derogatory and demeaning, and when you are in a position of power, being paid to treat vulnerable patients, that is not the time to promote your freedom of speech, especially knowing that it is perceived as cruel and abusive.