What does lesion mean?
A lesion is a localized area of abnormal tissue, injury, or structural change within an organ or other biological structure. In clinical and research language, the term is especially common for a discrete area of damage in the brain or nervous system, where it may describe both the altered tissue and the loss of function associated with it. The word can also denote a focal alteration in rock caused by processes such as heat or chemically active fluids, a more specialized geological use. Because lesion is more general and technical than wound, it covers microscopic damage, scarring, degeneration, tumors, and other pathological changes that may not resemble an open injury. In medicine, the specific cause and significance of a lesion depend on its location, size, and the findings of examination or imaging. The term is therefore useful in diagnosis, pathology, and scientific description, where precision about the affected tissue or functional area matters.
nounA lesion is a localized area of abnormal or damaged tissue in an organ or other part of the body. In geology and related technical fields, it can also refer to a focal area of altered material.
- A localized area of abnormal, injured, or diseased tissue, especially within an organ.
- An area of damage or abnormality in the brain or nervous system, often associated with an identifiable loss or alteration of function.
- In geology, a focal area of rock that has been altered by processes such as heat, pressure, or chemically active fluids.
"The scan revealed a small lesion in the left frontal lobe."
"The scan revealed a small lesion in the left frontal lobe."
"Petrographers identified a narrow lesion in the granite where hydrothermal fluids had altered the mineral assemblage."
The regular plural is used for multiple areas of tissue damage, disease, or abnormal change.
"Several lesions were visible throughout the liver."
A lesion is the body's scar on a map of damage: sometimes visible, often microscopic, and sometimes responsible for a specific loss of function.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does lesion come from?
English lesion derives from Latin laesionem, meaning “injury” or “damage,” a noun formed from the past participle stem of laedere, “to injure or hurt.” It entered Middle English in this form and later became established in medical usage for an area of damaged or diseased tissue. The French lédition, Spanish lesión, and Italian lesione developed through the same Latin tradition.
Related word forms
How lesion is actually used
Lesion is primarily a formal scientific and clinical term. It is broader than wound, covering microscopic injury, scarring, degeneration, tumors, and other abnormal tissue changes; in neurology, it can refer both to the affected tissue and to the associated functional impairment.
Easily confused with lesion
A lesson is something taught or learned, whereas a lesion is an area of tissue damage or abnormal change.