A term typically used pejoratively for what is seen as an obsessive avoidance of language or behaviour which might be perceived as offensive or discriminatory; thus ’vertically challenged’ is PC for short. The term originally referred to a US campus movement in the 1980s and early 1990s concerned to counter bias, discrimination, and ’hate speech’ arising from racism, sexism, and homophobia.
Chandler, Daniel - Munday, Rod (2011): Dictionary of Media and Communication. Oxford University Press. 326 p. See the online edition