Yes, it is considered an abnormal condition of mental ill-health and is listed in the International Classification of Diseases as 302.1 and is universally considered a mental disease by doctors.
Depends which psychiatric illness...
A symptom is a characteristic of illness, to which the antonym would be normality.
Yes
Hepatitis A
Not eating is a symptom of mental illness. It can also be a symptom of other medical problems. Since it is a symptom, it is extremely difficult to determine if it is a cause.
I would say its a symptom of something. You should get an appointment with the vet.
Yes, Diarrhea is a symptom of a disease or illness
Cachexia
This is likely a hallucination, which is a symptom of mental illness.
Pain is a symptom. It presents itself during illness or injury.
A fever is a sign of an illness, since it can be measured objectively.
A fever is a sign of an illness, since it can be measured objectively.