# lesion

/ˈɫiʒən/ (US) · /lˈiːʒən/ (UK)

Source: https://englishreference.com/word/lesion
Updated: 2026-08-27

## Senses

### 1. medical damage

noun · CEFR C1 · Technical

an area of the body, such as the skin or an organ, that has been damaged by a disease or an injury.

For teachers: a localized area of diseased or damaged tissue, such as a wound, ulcer, or tumor. Often used as a general term in clinical diagnosis before a specific cause is identified.

- The doctor examined the small red lesion on the patient's arm to see if it was an infection.
- The MRI scan revealed a small lesion in the left hemisphere of the brain, which explained the patient's sudden loss of motor coordination.

Usage: Commonly used with adjectives like 'skin', 'brain', 'benign', or 'malignant'.

### 2. legal imbalance

noun · CEFR C2 · Formal · Technical

a situation where a contract is so unfair that one person loses a lot of money.

For teachers: the injury or harm suffered by a party to a contract who does not receive the equivalent of what they give, potentially allowing the contract to be cancelled.

- The lawyer argued that the sale of the house was a case of lesion because the price was far too low.
- Under certain civil law jurisdictions, a contract may be rescinded on the grounds of lesion if the price paid is less than half the fair market value.

Teaching tip: This sense is rare outside of specific legal systems like those in France, Quebec, or Louisiana.

### 3. to cause damage

verb · CEFR C2 · Technical

to damage a specific part of a body, usually during a scientific experiment.

For teachers: to intentionally create a lesion in an organ or tissue, typically for the purpose of scientific research or medical treatment.

- Scientists lesioned a small part of the bird's brain to study how it learned songs.
- The researchers lesioned specific neural pathways in the laboratory mice to observe the resulting changes in social behavior.

Usage: This verb is transitive and almost exclusively used in academic or laboratory contexts.

## Examples

- The doctor examined the small lesion on his arm.
- After the biopsy, the dermatologist confirmed that the skin lesion was benign and required no further treatment.
- Advanced imaging techniques allow neurologists to identify the exact location of a brain lesion, which helps determine the specific cause of a patient's motor impairment.

---

From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.