radiation

Pronunciation

• IPA: /ˌɹeɪ.diˈeɪ.ʃən/^[1]

Etymology

It is Middle English radiacion, borrowed from Latin radiatio (“a shining, radiation”),^[2][3][4] a noun of action from radiāre (“to beam, shine”), from radius (“beam of light, spoke of a wheel”) (see radius and ray).^[2][5][6]

Earliest recorded meaning

The action of emitting light: the mid-15th century in Etymonline,^[2] late Middle English in SOED and NODE.^[4][5]

Semantic evolution

Rays or beams of light emitted are from the 1560s, 1570 in the OED.^[2][7] Divergence from a centre, a radial arrangement, is from 1658.^[7][2] The emission and spread of heat rays is from 1812–16,^[7] and in modern physics the emission of energy as waves or particles, especially ionizing radiation, from the early 20th century.^[2][7] Radiation sickness and radiation used as medical treatment (radiotherapy) follow.^[8][9] In biology, adaptive radiation is the spread of a group of organisms into new forms (1949).^[7]

Timeline

• mid-15th century – emission of light.^[2]
• 1570 – a ray of light.^[7]
• 1658 – divergence from a centre.^[7]
• 1812 – emission of heat.^[7]
• early 20th century – ionizing radiation.^[2]

Modern meaning

Noun

1. The emission of energy as electromagnetic waves or moving particles.
2. The energy emitted, especially the ionizing rays from radioactive substances.
3. Treatment of disease with radiation; radiotherapy.
4. Spreading out from a centre.

Word family

• radiational
• radiationless
• radiative
• antiradiation
• reradiation
• X-radiation
• background radiation
• electromagnetic radiation

Related words

• radiate
• radiant
• radius
• ray
• radio
• radium

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
3. ^ Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
4. ^ a b Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
5. ^ a b Pearsall, Judy, ed. (1998), The New Oxford Dictionary of English, Oxford: Clarendon Press
6. ^ Cresswell, Julia (2021), Oxford Dictionary of Word Origins, 3rd ed., Oxford: Oxford University Press
7. ^ a b c d e f g h Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press
8. ^ The American Heritage Dictionary of the English Language (1992), 3rd ed., Boston: Houghton Mifflin
9. ^ Collins English Dictionary (2023), Glasgow: HarperCollins