This term came out quite some time ago. It has come to be used almost exclusively in a manner perhaps not initially intended. Originally, it meant rephrasing an idea in such a way as to not cause offense. That is no longer its meaning in common usage. In the modern parlance, it is used almost solely as an expression of disgust that one can no longer “tell it like it is.” Of course, for the people who refer to “political correctness,” this also has a clear meaning:

“People who are not identical to me in one or more of the qualities of skin color, religion, ethnic background, gender, class, adherence to a political brand, etc. are subhuman filth and should be treated as such.”