Definition of "mental illness" []

• Any of various conditions characterized by impairment of an individual's normal cognitive, emotional, or behavioral functioning, and caused by social, psychological, biochemical, genetic, or other factors, such as infection or head trauma. Also called emotional illness, mental disease, mental disorder. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "I hated the whole religious kit and caboodle at such a young age, and still often wonder where the line of demarcation is between suffering from regular mental illness and just being Jewish."
• "At about the time when Phil conducted his Stanford prison experiment, a young psychiatrist named Frederick Melges began to investigate the relationship between time and mental illness on the same campus."
• "FOLSOM: Mrs. Speidel, has there been any mental illness on your side of the family?"