radiotherapy

Etymology

It is formed from English radio- + therapy,^{[2][3][4][5][6]} perhaps after French radiothérapie, recorded from 1898.^[3] Merriam-Webster calls it a word of the International Scientific Vocabulary.^[4] The OED compares German Radiotherapie and Italian radioterapia, both from 1903, and the earlier English radiotherapeutics.^[3] The first element is from Latin radius (“ray”),^[3] and therapy is from New Latin therapia, from Ancient Greek θεραπεία (therapeía, “healing, service done to the sick”).^[2]

Earliest recorded meaning

The treatment of disease by X-rays and other forms of ionizing radiation: 1902, in The Lancet.^[3][2][4] The 1989 edition of the OED had dated it to 1903.^[7]

Semantic evolution

The word was coined when X-rays and radium were first used in medicine, a few years after radiotherapeutics (1897).^[3] The form radio- had been used in English from the early 19th century, in anatomical terms for the radius bone, but from the late 19th century it became very frequent in scientific and medical words for radiation and radioactivity.^[3] It is used especially against cancer.^[3][8]

Timeline

• 1897 – the earlier radiotherapeutics.^[3]
• 1902 – treatment of disease by X-rays and other radiation.^[3][2][4]

Meanings

Noun

1. The treatment of disease, especially cancer, with X-rays or other ionizing radiation, either as a beam or from radioactive material placed in the body: After surgery she had six weeks of radiotherapy.^[8][4][3]

Word family

• radiotherapist

Related words

• radiation
• radium
• radius
• chemotherapy
• therapeutic

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
3. ^ a b c d e f g h i j k Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
4. ^ a b c d e Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
5. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
6. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
7. ^ Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press
8. ^ a b Collins English Dictionary (2023), Glasgow: HarperCollins