Social stigma
Social stigma is the severe disapproval of or discontent with a person on the grounds of characteristics that distinguish them from other members of a society.

Almost all stigma is based on a person differing from social or cultural norms
Norm (sociology)
Social norms are the accepted behaviors within a society or group. This sociological and social psychological term has been defined as "the rules that a group uses for appropriate and inappropriate values, beliefs, attitudes and behaviors. These rules may be explicit or implicit...

. Erving Goffman
Erving Goffman
Erving Goffman was a Canadian-born sociologist and writer.The 73rd president of American Sociological Association, Goffman's greatest contribution to social theory is his study of symbolic interaction in the form of dramaturgical perspective that began with his 1959 book The Presentation of Self...

 defined stigma as 'the process by which the reaction of others spoils normal identity'.

The three forms of stigma recognised by Goffman include: The experience of a mental illness (or the imposition of such a diagnosis); a physical form of deformity or an undesired differentness; and an association with a particular race, religion, belief, etc.