radiation English · revision 6729

+ {{infobox|confidence=established|formation=borrowing|attested=mid-15th century|origins=la radius}}

+

+ ==Pronunciation==

+ * IPA: /ˌɹeɪ.diˈeɪ.ʃən/^(Wiktionary)

+

+ ==Etymology==

+ It is Middle English radiacion, [[bor|la|radiatio|t=a shining, radiation]],^(Etymonline)^(MWU 2024)^(SOED 2002) a noun of action from [[m|la|radio|alt=radiāre|t=to beam, shine]], from [[m|la|radius|t=beam of light, spoke of a wheel]] (see [[radius]] and [[ray]]).^(Etymonline)^(NODE 1998)^(Cresswell 2021)

+

+ ==Earliest recorded meaning==

+ The action of emitting light: the mid-15th century in Etymonline,^(Etymonline) late Middle English in SOED and NODE.^(SOED 2002)^(NODE 1998)

+

+ ==Semantic evolution==

+ Rays or beams of light emitted are from the 1560s, 1570 in the OED.^(Etymonline)^(OED 1989) Divergence from a centre, a radial arrangement, is from 1658.^(OED 1989)^(Etymonline) The emission and spread of heat rays is from 1812–16,^(OED 1989) and in modern physics the emission of energy as waves or particles, especially ionizing radiation, from the early 20th century.^(Etymonline)^(OED 1989) ''Radiation sickness'' and radiation used as medical treatment (radiotherapy) follow.^(AHD)^(Collins 2023) In biology, ''adaptive radiation'' is the spread of a group of organisms into new forms (1949).^(OED 1989)

+

+ ==Timeline==

+ * mid-15th century – emission of light.^(Etymonline)

+ * 1570 – a ray of light.^(OED 1989)

+ * 1658 – divergence from a centre.^(OED 1989)

+ * 1812 – emission of heat.^(OED 1989)

+ * early 20th century – ionizing radiation.^(Etymonline)

+

+ ==Modern meaning==

+ ===Noun===

+ # The emission of [[energy]] as [[electromagnetic]] waves or moving [[particle|alt=particles]].^(AHD)^(Collins 2023)

+ # The energy emitted, especially the [[ionizing]] rays from [[radioactive]] substances.^(AHD)^(Collins 2023)

+ # Treatment of disease with radiation; [[radiotherapy]].^(AHD)^(Collins 2023)

+ # Spreading out from a centre.^(AHD)^(SOED 2002)

+

+ ==Word family==

+ * [[radiational]]

+ * [[radiationless]]

+ * [[radiative]]

+ * [[antiradiation]]

+ * [[reradiation]]

+ * [[X-radiation]]

+ * [[background radiation]]

+ * [[electromagnetic radiation]]

+

+ ==Related words==

+ * [[radiate]]

+ * [[radiant]]

+ * [[radius]]

+ * [[ray]]

+ * [[radio]]

+ * [[radium]]

+

+ ==References==

+ {{reflist}}