mental disorder

1. abnormal anxiety about one's health, especially with an unwarranted fear that one has a serious disease.
4. a mental illness that causes unusual shifts in mood, energy, activity levels, concentration, and the ability to carry out day-to-day tasks.
6. any disorder that significantly impairs the cognitive function of an individual to the point where normal functioning in society is impossible without treatment.
7. medical practitioner specializing in the diagnosis and treatment of mental illness.
11. a chronic or persistent disorder of the mental processes caused by brain disease or injury and marked by memory disorders, personality changes, and impaired reasoning.
12. a long-term mental disorder of a type involving a breakdown in the relation between thought, emotion, and behavior, leading to faulty perception, inappropriate actions and feelings, withdrawal from reality and personal relationships into fantasy and delusion, and a sense of mental fragmentation.

2. a mental health condition that's triggered by a terrifying event — either experiencing it or witnessing it.
3. an expert or specialist in psychology.
5. a type of behavior disorder.
8. short for obsessive-compulsive disorder.
9. attack a sudden feeling of acute and disabling anxiety.
10. of sadness, tearfulness, emptiness or hopelessness.