The quality of being unhealthful or diseased, sometimes including the cause.
The quality of being morbid; an attitude or state of mind marked by gloom.
(medicine) The incidence of a disease, as a rate of a population which is affected.
(medicine, countable) An occurrence of illness or disease, or a single symptom of that illness.
(medicine, countable) Adverse effects caused by a medical treatment such as surgery.
(demography, insurance) The sickness rate of a population.