“Brief, everyday exchanges that send denigrating messages to certain individuals because of their group membership.”
"It is important for people to realize that contrary to a belief that microaggressions do minimal harm, research reveals that they oppress, create disparities in our society toward marginalized groups, and contribute to psychological stress and distress for these groups."
Derald Wing Sue, Microaggressions in Everyday Life
Labeling people as ‘The mentally ill’ increases stigma
by Darcy Haag Granello, Professor of Counselor Education, The Ohio State University
http://theconversation.com/labeling-people-as-the-mentally-ill-increases-stigma-53794
“When people in our study saw the term “the mentally ill,” they were more likely to believe the people described by the label are dangerous, violent and need coercive handling. They were also more likely to perceive them as inferior and to treat them like children, or to try to distance themselves and their communities from interactions with the people described, and less likely to want to spend tax dollars to help them. Those are some powerful reactions, and they deserve a powerful response.”
Microaggressions in Everyday Life by 
That's So Gay! by