# tumor

/ˈtumɝ/ (US) · CEFR B2 · Noun

Source: https://englishreference.com/word/tumor
Updated: 2026-05-02

## Definition

a mass of extra cells that grows in or on the body. Some are harmless, but others can cause serious health problems like cancer.

For teachers: an abnormal mass of tissue resulting from excessive cell division. It may be benign, meaning it does not spread, or malignant, indicating a cancerous growth.

## Examples

- The doctor found a small tumor during the routine scan.
- After the biopsy, the medical team confirmed that the tumor was benign and required no further treatment.
- Advances in oncology have allowed surgeons to target the tumor with extreme precision, minimizing damage to the surrounding healthy tissue during the procedure.

## Usage notes

- Commonly modified by the adjectives 'benign' or 'malignant' to indicate the level of health risk.

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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.