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

Climbing to such a height – three times higher than the International Space Station – took the vehicle through the treacherous inner regions of Earth's Van Allen radiation belts. —Eric Lagatta, USA TODAY, 16 Sep. 2024

The mission had several other potentially dangerous components, including passing through a radiation belt that exposed the crew to the same levels of radiation that astronauts would receive in two months aboard the International Space Station. —Daniel Cote, Robb Report, 16 Sep. 2024

Months of chemotherapy and radiation followed, along with and six surgeries, including a double mastectomy and a recent procedure over the summer to remove her ovaries. —Eileen Finan, Peoplemag, 14 Sep. 2024

Polaris Dawn is also going to be venturing to a part of space no one has reached since the 1970s, which comes with possible hazards of extra radiation and micrometeorites that could potentially puncture a space suit. —Briley Lewis, Popular Science, 11 Sep. 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