mental illness (countable and uncountable, plural mental illnesses)
- (uncountable) The property of being mentally ill; mental disorders taken as a whole.
- 2006, R. Keith Sawyer, Explaining Creativity: The Science of Human Innovation, Oxford University Press US, ISBN 9780195161649, page 87:
- Such studies show that geniuses are not any more likely to suffer from mental illness than the rest of us.
- (countable) A mental disorder.
- 2002, Vikram Patel, Where There is No Psychiatrist: A Mental Health Care Manual, RCPsych Publications ISBN 978-1-901242-75-1, page 70:
- Epilepsy is not a mental illness. It is caused by electrical changes in the brain.
- The uncountable sense is far more common than the countable.
a mental disorder (countable)