When "politically correct" is used as an attack on someone else's words, it nearly always means "being polite to a person or group the attacker dislikes".
When "politically correct" is used by a small number of academic theorists to describe the conscious substitution of vocabulary in order to conform to a particular subculture, it means... what I just said.
There are a reasonably large number of people who think that the second definition describes every situation actually covered by the first.