pathological

/ˌˈpæθəˌlɑdʒəkəl/

If something is caused by a physical or mental disease, it is pathological. Someone with a pathological compulsion for cleanliness might scrub the floors for hours every night.

Pathological comes from a Greek word, pathologikos, which means “treating of diseases” — pathos means "suffering." Anyone who studies or works with diseases, from their causes to their symptoms, identifies how the disease affects its victims, in other words, its pathological effects. Remember that this is a medical distinction. If a person has, for example, obsessive-compulsive disorder, his or her repetitive actions are pathological.

Definitions of pathological

1. adjective

   of or relating to the practice of pathology
   “pathological laboratory”

   synonyms: pathologic
2. adjective

   caused by or evidencing a mentally disturbed condition
   “a pathological liar”

   “a pathological urge to succeed”

   synonyms:

   neurotic, psychoneurotic

   affected with emotional disorder
3. adjective

   caused by or altered by or manifesting disease or pathology
   “pathological bodily processes”

   synonyms: diseased, morbid, pathologic

   unhealthy

   not in or exhibiting good health in body or mind