Diseased

Diseased is an adjective used to describe something that is affected by disease. It applies to organisms, tissues, or ecosystems, and it appears in medical, veterinary, botanical, and scientific writing.

In clinical and laboratory contexts, diseased is paired with nouns such as tissue, organ, or patient to denote pathological change. Examples include diseased tissue, diseased heart, or diseased animals. The term emphasizes the presence of disease rather than general illness.

In plants, wildlife, and microbes, diseased can describe hosts harmed by pathogens, parasites, or abiotic stress. For example, diseased leaves caused by fungi or diseased coral from environmental damage. In microbiology, terms like diseased bacteria or diseased viruses refer to organisms that cause disease, or to states of pathology in a host.

Connotation and usage vary by context. In everyday language, diseased is more formal and clinical than words like sick or ill. It can be stigmatizing when applied to people outside professional contexts. Some writers prefer disease- or illness-specific terms or phrases such as disease-affected rather than diseased, depending on the precision needed.

Related terms include disease, illness, infection, and pathology. Antonyms include healthy, well, and disease-free. The phrase diseased tissue is common in pathology reports, and diseased populations may appear in epidemiology and public health discussions.