diseased
Americanadjective
adjective
Other Word Forms
- nondiseased adjective
- undiseased adjective
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.
To prepare for transplant, I had two weeks of near-lethal doses of chemo to destroy my diseased bone marrow and suppress my immune system, creating space for donor cells to take hold.
From The Wall Street Journal • Apr. 19, 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
Surgeons have told the BBC that healthy organs can be discarded, and diseased organs can be transplanted.
From BBC • Mar. 24, 2026
When they detect danger, they process fragments of abnormal proteins and present them as antigens to T cells, which then seek out and destroy diseased or cancerous cells.
From Science Daily • Jan. 16, 2026
Sometime in the late nineteenth century clumsy repairs were made with unpainted cement which had turned brown and gave the building a mottled, diseased appearance.
From "Atonement" by Ian McEwan
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.
