tumor

/ˈtuːmər/
noun
  1. An abnormal mass of tissue in the body that grows more quickly than normal cells and serves no useful purpose. Tumors can be benign (not harmful) or malignant (cancerous).
    • The doctor found a small tumor in her lung during the X-ray.
    • He underwent surgery to remove a tumor from his brain.
    • Most tumors in the breast are benign and not life-threatening.
Synonyms