What does cancer mean?
Cancer is a noun denoting one of medicine's most serious diseases: a condition in which the body's own cells grow uncontrollably, forming malignant tumours that can invade nearby tissues and spread to distant organs through the blood and lymphatic system. Because it encompasses more than a hundred distinct diseases — from breast and lung cancer to leukaemias and lymphomas — the term functions as an umbrella label rather than a single illness. Beyond medicine, the word has a long-established figurative use, describing anything corrupt or destructive that insidiously spreads through a community, institution, or relationship. Its connotations are uniformly grave, so writers employ it deliberately and often metaphorically. The name itself traces back to ancient Greece, where physicians likened tumours to crabs, giving the word a vivid etymology rooted in classical observation.
A malignant disease of the body's cells, marked by uncontrolled division, invasion of surrounding tissue, and potential spread (metastasis) to other organs.
"Early diagnosis greatly increases the chances of successfully treating cancer."
Often used with a specifying adjective (e.g. skin cancer, pancreatic cancer) since the term covers many distinct malignancies.
Something evil or destructive that grows and spreads gradually and harmfully, especially within a society or organization.
"He described bribery as a cancer that would eventually destroy public trust."
The plural 'cancers' usually refers to multiple cases or types of the disease rather than multiple tumours in one person.
"Researchers studied how cancers differ across populations worldwide."
The word 'cancer' comes from the Greek karkinos — Hippocrates named the disease after a crab because swollen veins around tumours resembled crab legs.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cancer
The English word 'cancer' derives directly from Latin cancer, meaning 'crab', which the Romans used to translate the Greek karkinos ('crab'), the term applied to the disease by Hippocrates and later Galen. The comparison arose because hardened, vein-spread tumours were thought to resemble a crab's limbs. The related Old French form cancre produced the English variant 'canker', which survives in narrower meanings such as plant diseases and mouth ulcers. Both ultimately trace to the same Indo-European root that also gave words like 'cancel' and 'chancellor'.
Related word forms
How cancer is actually used
In medical contexts, 'cancer' is a broad umbrella term covering over a hundred distinct malignancies, so clinicians often prefer naming the specific type. The figurative sense carries strong negative connotation and should be used with care; referring to people as a 'cancer' on a team or group is widely considered dehumanizing. In British English the word is sometimes pronounced with a long 'a' (/ˈkɑːnsə/), though /ˈkænsər/ is standard in both regions today.
Easily confused with cancer
Canker is an older term for an ulcerating sore (and for plant diseases), whereas cancer refers specifically to the modern medical disease of uncontrolled cell growth.