radiation

noun

ra·​di·​a·​tion ˌrā-dē-ˈā-shən 

1

a

: the action or process of radiating

b

: the process of emitting radiant energy in the form of waves or particles

c(1)

: the combined processes of emission, transmission, and absorption of radiant energy

(2)

: the transfer of heat by radiation compare conduction, convection

2

a

: something that is radiated

b

: energy radiated in the form of waves or particles

3

: radial arrangement

4

: adaptive radiation

radiational

ˌrā-dē-ˈā-shnəl 

-shə-nᵊl

adjective

radiationless

ˌrā-dē-ˈā-shən-ləs 

adjective

radiative

ˈrā-dē-ˌā-tiv 

adjective

Examples of radiation in a Sentence

She was exposed to high levels of radiation.

He goes in for radiation next week.

the sun's radiation of heat

Recent Examples on the Web

On the surface, those who weren’t killed by the blasts were affected by the radiation, their children and grandchildren growing up in a violent world of starvation, addiction, and zombie-like human mutates known as Ghouls. —Richard Newby, TIME, 12 Apr. 2024

Citizens must live in underground bunkers to protect themselves from radiation, mutants and bandits after nuclear annihilation. —Anna Tingley, Variety, 10 Apr. 2024

Basically, sun exposure bombards your skin cells with ultraviolet (UV) radiation. —Jessica Chia, SELF, 9 Apr. 2024

Does an eclipse emit special radiation that can instantly blind you? —Bill Chappell, NPR, 8 Apr. 2024

Cancer survivors often show greater biological aging, perhaps because of the after effects of therapies like chemotherapy and radiation. —Brenda Goodman, CNN, 7 Apr. 2024

That international safety standard, which is set by the International Organization for Standardization, means the glasses reduce visible sunlight to a safe level and block ultraviolet and infrared radiation, according to the American Astronomical Society website. —S. Dev, CBS News, 4 Apr. 2024

Astronomers tracking the comet since 2022 have observed violent eruptions as solar radiation heats the comet's core, according to the British Astronomical Association. —USA TODAY, 2 Apr. 2024

In 1967, Wheeler attended a discussion of the astrophysicist Jocelyn Bell’s recent discovery of pulsars—celestial objects that flash out radiation. —Rivka Galchen, The New Yorker, 30 Mar. 2024

Word History

First Known Use

15th century, in the meaning defined at sense 1a

Phrases Containing radiation

• adaptive radiation
• anti-radiation
• background radiation
• Cerenkov radiation
• cosmic background radiation
• electromagnetic radiation
• gamma radiation
• gravitational radiation
• radiation sickness
• radiation therapy
• secondary radiation
• synchrotron radiation
• x-radiation

Kids Definition

radiation

noun

ra·​di·​a·​tion ˌrād-ē-ˈā-shən 

1

: the action or process of radiating

especially : the process of giving off radiant energy in the form of waves or particles

2

: something that is radiated

especially : energy radiated in the form of waves or particles

radiational

-shnəl 

-shən-ᵊl

adjective

Medical Definition

radiation

noun

ra·​di·​a·​tion ˌrād-ē-ˈā-shən 

1

: energy radiated in the form of waves or particles

2

a

: the action or process of radiating

with radiation of the pain there may be tenderness over the sciatic nerve

—J. A. Key

b(1)

: the process of emitting radiant energy in the form of waves or particles

(2)

: the combined processes of emission, transmission, and absorption of radiant energy

3

: a tract of nerve fibers within the brain

especially : one concerned with the distribution of impulses arising from sensory stimuli to the relevant coordinating centers and nuclei

the optic radiations