cancer [OE] The pattern of swollen veins around malignant tumours gave them the name cancer because they looked like the limbs of a crab—cancer in Latin—hence the name of the astrological sign. In English canker [ME] was the usual form for the disease until the 17th century, when canker became the term for various plant diseases. The medical term carcinoma [L16th] comes from karkinos, Greek for ‘crab’.