9:50 AM PT -- Kim has apologized for using the word, telling us, "I want to apologize for what I said in a recent video post that is inappropriate and insensitive to the special needs community. I try to learn from my mistakes and this is one of those times. Please know that my intention is always pure, and in this case, it was a mistake. I’m sorry."

Another huge star has offended the special needs community -- this time, it's Kim Kardashian West who used the r-word to insult Halloween party guests who couldn't guess her costume.

Kim dressed up as Pam Anderson to attend Kendall Jenner's Halloween bash Wednesday night -- but was jokingly irritated when she quizzed guests about her costume and they couldn't figure it out.

But, in a video Kim posted -- and has since deleted -- on Instagram to her 120 MILLION followers, Kim used the word "r******d" to describe guests who were too dumb to decipher her Halloween character.

Of course, the problem ... tons of special needs groups have spoken out about the dangers of using the r-word because it essentially uses a serious condition as an insult.

In fact, earlier this week, Shaun White issued an apology after dressing as a special needs character from the movie "Tropic Thunder" for a Halloween party.

Bottom line -- special needs people are not punchlines, insults or Halloween costumes and people like Kim and Shaun should be more understanding.

Kim deleted the video off her IG page, but the internet backlash was immediate. Some comments about the clip ...

"@KimKardashian using the R word on her IG story from yesterday is disgusting. And I really liked her. Watched, followed, bought shit, spent like 3 grand on her game. My brother is an ANGEL sent from Heaven and if you use it generally, you use it ALL THE TIME. Done."

"It's 2018, we don't say the r word anymore."

"Ughh @KimKardashian saying the R word in her IG story made me cringe."

Originally published -- 8:03 AM PDT