the use of chemical agents to treat or control disease (or mental illness)
"The doctor recommended chemotherapy to help control the spread of cancer in her body."
Any chemical treatment intended to be therapeutic with respect to a disease state.
"The patient underwent chemotherapy as part of their plan to treat cancer."
In plain English: Chemotherapy is medicine used to kill cancer cells throughout your body by attacking them with strong drugs.
"The doctor explained that chemotherapy would be necessary to treat her cancer."
Usage: Chemotherapy specifically refers to cancer treatments that use drugs to kill rapidly dividing cells, distinguishing it from other medical therapies like radiation or surgery. It is often shortened in conversation to "chemo," but the full term should only describe this targeted drug therapy for malignancies.
The word chemotherapy combines the prefix chemo- with therapy to describe medical treatment using chemical substances. It entered English as a compound term that directly reflects its method of action rather than undergoing a significant shift in meaning over time.