I’m not saying this is the official definition of political correctness, but this is mine that I believe others share. And by the way, I’m not a fan of political correctness, except as it relates to slurs and perhaps racial, ethnic and sexist jokes. But political correctness are terms and phrases that are considered by lets say the broader public as acceptable. And something that is not considered politically correct is considered offensive. No racial and ethnic slurs by a majority if not most Americans are generally considered offensive and politically incorrect. Only the Far-Right and Far Left approve of them. Well they approve of the slurs against people they disapprove of.
The extreme version of political correctness which is really a form of fascism, is when people criticize members of minority groups and minority groups in general. And they don’t even use bigoted language. Like with Bill Maher back in September and October criticizing Islam and certain aspects of it, accurately so I might add. And the Far-Left who use to admire Maher now viewing him as a racist for criticizing Islam even though his critique was factually based. But since Muslims are a religious, not ethnic or racial minority in the country, the Far-Left jumped on Bill Maher and called him a bigot if not racist for his critique of Islam.
I agree that people who use offensive language against members of groups or groups in general, especially when they are inaccurate and are intentionally being offensive should be looked down upon as bigots and people who aren’t very bright and everything else. But that is different from saying someone should automatically be fired or not allowed to speak simply because they say things that is offensive. Whether its Rush Limbaugh or Michael Savage on the Far-Right, or Michael Moore on the Far-Left. People on the fringes in America have the same free speech rights as people in the mainstream. So when political correctness becomes fascism is when I have a real problem with it as a Liberal who loves free speech and the First Amendment.
GBPPR: The History of Political Correctness