Quantcast
Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Medical
  • Scrabble
  • Spanish Central
  • Learner's Dictionary

background radiation

noun

Definition of background radiation

  1. :  the microwave radiation pervading the universe that exhibits a corresponding blackbody temperature of 2.7 K and that is the principal evidence supporting the big bang theory —called also cosmic background radiation



1968

First Known Use of background radiation

1968


Seen and Heard

What made you want to look up background radiation? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

a smart aleck

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

image567572573

Which of these is a synonym of unctuous?

oily angry maudlin prompt
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ