chemotherapy

noun

che·​mo·​ther·​a·​py ˌkē-mō-ˈther-ə-pē 

: the therapeutic use of chemical agents to treat disease

especially : the administration of one or more cytotoxic drugs to destroy or inhibit the growth and division of malignant cells in the treatment of cancer

Note: Chemotherapy may be used alone as a primary treatment or may be used before, after, or in conjunction with surgery or radiation.

called also chemo

chemotherapist

ˌkē-mō-ˈther-ə-pist 

noun

Examples of chemotherapy in a Sentence

Recent Examples on the Web

Other forms of menopause include surgical, which is triggered by a hysterectomy to remove the uterus and ovaries, and medical menopause, where treatments such as chemotherapy or radiation therapy may affect the functioning of the ovaries and result in the onset of menopause. —Sashikala Vp, CNN Money, 4 Dec. 2025

On the right ‘Tract’ The company is focused on stem cell cloning technology, which allows researchers to isolate single cells from samples like tumor biopsies in cases that have failed first- or second-line chemotherapy. —Charlotte Observer, 4 Dec. 2025

To compound the strangeness of the disorder, THC and other cannabinoids in the marijuana plant have been used for pain relief — paradoxically relieving nausea and vomiting in cancer patients undergoing chemotherapy. —Cnn.com Wire Service, Mercury News, 3 Dec. 2025

After surgery, Tom went through chemotherapy and radiation at the Royal Marsden Hospital in Chelsea. —Vanessa Etienne, PEOPLE, 3 Dec. 2025

Word History

Etymology

borrowed from German Chemotherapie, from chemo- chemo- + Therapie therapy

Note: The German word Chemotherapie is strongly associated with Paul ehrlich, though it is uncertain if he is its originator. Ehrlich probably first used the word in print in the article "Chemotherapeutische Trypanosomen-Studien," Berliner klinische Wochenschrift, 44. Jahrgang, No. 9 (March 4, 1907), pp. 233-36 (along with the Latin equivalent chemotherapia in the phrase chemotherapia specifica). Ehrlich employed the word earlier, however, in an address read at the dedication of the Georg-Speyer-Haus in Frankfurt am Main on September 6, 1906. What appears to be a summary of the address was published as "Die Aufgaben der Chemotherapie" ("The Tasks of Chemotherapy") in the feuilleton section of the Frankfurter Zeitung und Handelsblatt, 51. Jahrgang, No. 244, September 4, 1906, p. 1. The full text of the address ("Ansprache bei Einweihung des Georg-Speyer-Hauses") was published for the first time in The Collected Papers of Paul Ehrlich, edited by F. Himmelweit, vol. III Chemotherapy (London, 1960), pp. 42-52.

First Known Use

1910, in the meaning defined above

Rhymes for chemotherapy

• brachytherapy
• cryotherapy
• hydrotherapy
• hypnotherapy
• monotherapy
• phototherapy
• psychotherapy
• sclerotherapy
• immunotherapy
• pharmacotherapy
• physiotherapy
• radiotherapy

Kids Definition

chemotherapy

noun

che·​mo·​ther·​a·​py ˌke-mō-ˈther-ə-pē 

: the use of chemical agents in the treatment or control of disease (as cancer)

chemotherapeutic

-ˌther-ə-ˈpyüt-ik

adjective

Medical Definition

chemotherapy

noun

che·​mo·​ther·​a·​py -ˈther-ə-pē 

plural chemotherapies

: the therapeutic use of chemical agents to treat disease

Pyrazinamide is one of the most important drugs in modern chemotherapy of tuberculosis …

—Max Salfinger et al., The Journal of the American Medical Association

especially : the administration of one or more cytotoxic drugs to destroy or inhibit the growth and division of malignant cells in the treatment of cancer

Cancer cells mutate at a furious rate, and they can evolve the means to resist most chemotherapy drugs, requiring higher and more toxic doses to achieve an effect.

—Shannon Brownlee and Nancy Shute, U.S. News & World Report

Neutropenia and infection are major dose-limiting side effects of chemotherapy.

—Jeffrey Crawford et al., The New England Journal of Medicine

called also chemo

Note: Chemotherapy may be used alone as a primary treatment or may be used before, after, or in conjunction with surgery or radiation.