diseased
Americanadjective
adjective
Other Word Forms
Etymology
Origin of diseased
1425–75; late Middle English disesed; compare Anglo-French diseasé. See disease, -ed 2
Explanation
When something is unhealthy or affected by illness, it's diseased. Sadly, the diseased trees in the city park may eventually need to be cut down and removed. While this adjective essentially means "sick," it's not generally used to describe people. Instead, you might use it for plants, animals, or body parts: "Hepatitis can result in a diseased liver." Diseased comes from the Old French desaise, "discomfort or sickness," from des-, "without," and aise, "ease."
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Surgical options for younger patients include a Ross procedure, in which a patient’s diseased aortic valve is replaced with their own healthy pulmonary valve, which in turn is replaced with a donor valve.
From The Wall Street Journal • Apr. 25, 2026
Research focused on using chemotherapy and radiation to wipe out diseased bone marrow, then infusing healthy donor cells to create a new immune system capable of attacking cancer and rebuilding the body’s defenses.
From The Wall Street Journal • Apr. 19, 2026
In medicine, they could function as "nano-surgeons," locating diseased cells and delivering targeted treatments with precision.
From Science Daily • Mar. 31, 2026
Surgeons have told the BBC that healthy organs can be discarded, and diseased organs can be transplanted.
From BBC • Mar. 24, 2026
This meant that passengers and crew were trapped on board with successive generations of diseased insects.
From "An American Plague: The True and Terrifying Story of the Yellow Fever Epidemic of 1793" by Jim Murphy
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
