Definition of "Cancer" :

noun: type genus of the family Cancridae

noun: the fourth sign of the zodiac; the sun is in this sign from about June 21 to July 22

noun: a small zodiacal constellation in the northern hemisphere; between Leo and Gemini

noun: (astrology) a person who is born while the sun is in Cancer

noun: any malignant growth or tumor caused by abnormal and uncontrolled cell division; it may spread to other parts of the body through the lymphatic system or the blood stream