Just Down, not Down’s (I didn’t know that either!). Syndrome isn’t capitalized. Unless it is at the beginning of a sentence.
The name comes from Dr. John Langdon Down who defined the syndrome in the mid 1800’s. (It would be another 100 years before scientists figured out that Down syndrome was caused by an extra 21st chromosome.)
Within the disability community there is a movement toward “people first” language. This means that the names of conditions are used as descriptions only. So a person with Down syndrome is not referred to as a Down syndrome, a Down, or a Down’s. I think all of those just sound plain awkward, but I’ve heard them a few times. The approved form is “with Down syndrome,” as in “babies with Down syndrome tend to have low muscle tone,” or “I have a son with Down syndrome.” Until I’d read more about this preference, I used phrases like “Down’s babies,” so I’m not offended by that language. But I figure I’ll take the advice of folks who have been advocating for their friends & family members longer than I, and I’ll try to make my language reflect their wishes.
I also see the abbreviations Ds and DS quite often. If you don’t see those around this blog, well, that’s just because I don’t like to abbreviate much when I’m typing.
More generally, children have “developmental delays” and adults with special needs are said to have “developmental disabilities.” The term “special needs” kind of drives me nuts (don’t we all have special needs?), but I also kind of like its gentle familiarity. It does sound less clinical than “developmental delay.”
Friends and family who support the inclusion of their loved ones with Down syndrome in their lives and in their community are "advocates." I've been seeing adults with Down syndrome (and other developmental disabilities) referred to as "self-advocates," and I like that term.
As for the “R” word, really? Do we even have to have this discussion? I’ve never used the word because it’s just never been a part of the vocabulary around me. And now, when I do hear it, I am reminded of the day, not too long in the future, when I will have to explain the word, its history, and its use as an insult, to my son. So I might understand when your 90 year old grandma uses it, but in all other cases it’s just not acceptable.
Actually, I have a friend in her 90’s, and I’m pretty sure she hasn’t used the word in 50 years. So if she can’t use the clinical/historical/old-habit excuse, then you can’t either.