cancer
noun
cancer
American
[kan-ser]
/ ˈkæn sər /
noun
Cancri
genitive
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Pathology.
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a malignant and invasive growth or tumor, especially one originating in epithelium, tending to recur after excision and to metastasize to other sites.
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any disease characterized by such growths.
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any evil condition or thing that spreads destructively; blight.
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(initial capital letter) the Crab, a zodiacal constellation between Gemini and Leo.
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Astrology. Cancer,
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the fourth sign of the zodiac: the cardinal water sign.
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a person born under this sign, usually between June 21 and July 22.
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tropic of Cancer. tropic1a
Cancer
1
British
/ ˈkænsə /
noun
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astronomy a small faint zodiacal constellation in the N hemisphere, lying between Gemini and Leo on the ecliptic and containing the star cluster Praesepe
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astrology
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Also called: the Crab. the fourth sign of the zodiac, symbol ♋, having a cardinal water classification and ruled by the moon. The sun is in this sign between about June 21 and July 22
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Also called: Moonchild. a person born during a period when the sun is in this sign
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See tropic
adjective
cancer
2
British
/ ˈkænsə /
noun
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any type of malignant growth or tumour, caused by abnormal and uncontrolled cell division: it may spread through the lymphatic system or blood stream to other parts of the body
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the condition resulting from this
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an evil influence that spreads dangerously
Cancer
1
Scientific
cancer
2
Scientific
/ kăn′sər /
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A disease characterized by any of various malignant neoplasms composed of abnormal cells that tend to proliferate rapidly and invade surrounding tissue. Without treatment such as chemotherapy or radiation, cancer cells can metastasize to other body sites and cause organ failure and death.
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A malignant tumor.
cancer
Cultural
Usage
What does Cancer mean? Cancer is the name of a constellation that’s interpreted as resembling a crab. It’s sometimes referred to as The Crab. A constellation is a group of stars that appear near each other in the sky—especially a group that has been given a name. Cancer is considered one of the 12 zodiacal constellations—constellations that appear within a particular portion of the sky called the zodiac. In astronomy, the zodiac is the band of sky along which the paths of the sun, the moon, and the planets appear to move. Despite its basis in astronomy, the word zodiac is mainly associated with and most often used in the context of astrology, the nonscientific practice in which the positions of heavenly bodies at certain times are thought to influence or be correlated with human behavior and events. In astrology, zodiac refers to a diagram (often a circular one) representing the zodiac belt and showing the symbols associated with each of the 12 constellations or sections, which are called the signs of the zodiac. Cancer is one of these signs. It is situated between Gemini and Leo and is considered the fourth sign of the zodiac. The other signs of the zodiac are Aries, Taurus, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces. The position of the sun in a particular portion of the zodiac at the moment of a person’s birth is thought to correlate with their personality. This is what people are referring to when they talk about their zodiac sign (or star sign or often just sign). People whose sign is Cancer are those born between June 21 and July 22. In the context of the zodiac, the word Cancer can also be used as a noun to refer to someone who is born during this time, as in I was born in early July, so I’m a Cancer. The word Cancerian can be used to mean the same thing. It can also be used as an adjective form of Cancer. Example: I’m a Cancer, but I don’t think I fit into the sensitive Cancer stereotype.
Closer Look
The human immune system often fights off stray cancer cells just as it does bacteria and viruses. However, when cancer cells establish themselves in the body with their own blood supply and begin replicating out of control, cancer becomes a threatening neoplasm, or tumor. It takes a minimum of one billion cancer cells for a neoplasm to be detectable by conventional radiology and physical examinations. Cancer, which represents more than 100 separate diseases, destroys tissues and organs through invasive growth in a particular part of the body and by metastasizing to distant tissues and organs through the bloodstream or lymph system. Heredity, lifestyle habits (such as smoking), and a person's exposure to certain viruses, toxic chemicals, and excessive radiation can trigger genetic changes that affect cell growth. The altered genes, or oncogenes, direct cells to multiply abnormally, thereby taking on the aggressive and destructive characteristics of cancer. Treatments such as surgery, chemotherapy, and radiation are effective with many cancers, but they also end up killing healthy cells. Gene therapy attempts to correct the faulty DNA that causes the uncontrolled growth of cancer cells. Researchers are investigating other treatments, such as immunotherapy (the stimulation of the body's natural defenses), vectorization (aiming chemicals specifically at cancer cells), and nanotechnology (targeting cancer cells with minute objects the size of atoms).
Discover More
The term cancer is often used to describe a nonmedical condition that is undesirable, destructive, and invasive: “Watergate was a cancer on the presidency.”
Other Word Forms
Etymology
Origin of cancer
First recorded in 1350–1400; Middle English, from Latin: literally, “crab”; Latin stem cancr-, dissimilated from unattested carcr-, akin to Greek karkínos, Sanskrit karkata “crab”; see canker
Explanation
Cancer is a disease in which cells grow uncontrollably and form tumors. The best chance of surviving cancer usually involves finding and treating it early. The word cancer actually means "crab," like the zodiac sign. Around 400 B.C., Greek physician Hippocrates is said to have named the disease karkinos, which is Greek for "crab," when he noticed that tumors formed a crab-like shape. The word cancer describes not just a disease, but any sort of evilness that can spread. Hatred and bigotry are cancers that can destroy communities.
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
For The Telegraph, Neill also discussed his humble upbringing, how he felt his acting career had been a “complete fluke” and his perspective on life amid his cancer battle.
From Los Angeles Times ● Jul. 15, 2026
Many of the altered genes and biological processes have already been linked to cancer in humans and other animals.
From Science Daily ● Jul. 15, 2026
Read: This disease is more expensive than cancer and heart disease combined.
From MarketWatch ● Jul. 15, 2026
In May 2025, just four months after he left office as the oldest sitting president, Biden revealed that he had been diagnosed with an aggressive form of prostate cancer that had spread to his bones.
From Barron's ● Jul. 15, 2026
The lumberjacks and environmentalists love me equally, but a problem arises when a group of lesser scientists spread the rumor that the leaves of my trees cause cancer in laboratory animals.
From "Me Talk Pretty One Day" by David Sedaris
To better understand why, researchers launched the Epidemiology of Young Lung Cancer Project.
From Science Daily ● Jul. 13, 2026
That work led to a 2000 article in the Journal of the National Cancer Institute demonstrating that HPV-related cases were very different from those related to tobacco or alcohol—and less deadly.
From The Wall Street Journal ● Jul. 10, 2026
Murphy also is a research member at Siteman Cancer Center, based at Barnes-Jewish Hospital and WashU Medicine.
From Science Daily ● Jul. 9, 2026
Cancer is not the death sentence it used to be, but the sooner you catch it, the better the outcome.
From Los Angeles Times ● Jul. 7, 2026
When she told him she was a patient aide at Baltimore City Hospital, he said, “Really? I work at the National Cancer Institute.”
From "The Immortal Life of Henrietta Lacks" by Rebecca Skloot
One of the most well-known of these mysterious burning worlds is 55 Cancri e, an exoplanet about 41 light-years away that scientists describe as home to both sparkling skies and roiling lava seas.
From Science Daily ● Sep. 27, 2023
Scientists hope to learn whether 55 Cancri e even has an atmosphere, and if so what is it made of.
From Salon ● Sep. 15, 2022
The two planets Webb officials highlighted include the super-hot, lava-covered 55 Cancri e, and LHS 3844 b, which lacks a substantial atmosphere.
From Scientific American ● Jun. 3, 2022
Initial views from NASA’s less-powerful Spitzer Space Telescope show something mysterious is happening on 55 Cancri e, because the hottest spot is not the part directly facing its star.
From Seattle Times ● May 31, 2022
There is, however, a third star, known as 20 Cancri, near the same place, and this Watson probably mistook for Theta.
From The Story of the Heavens by Ball, Robert S. (Robert Stawell), Sir
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
