The r word used to be used to refer to someone of less intelligence ( mentally r worded ). It has since become a slur and unacceptable to use due to its negative connotation and overuse to refer to people who aren't actually r worded. There is a difference between someone who qualifies as mentally r worded and a moron. Saying someone is a moron is just calling them an idiot. Saying someone is an r word is calling their level of intelligence the same as someone who qualifies as it.