cosmic ray

noun

Definition of cosmic ray

  1. :  a stream of atomic nuclei of extremely penetrating character that enter the earth's atmosphere from outer space at speeds approaching that of light

First Known Use of cosmic ray

1925


COSMIC RAY Defined for English Language Learners

cosmic ray

noun

Definition of cosmic ray for English Language Learners

  • : a stream of energy that enters the Earth's atmosphere from outer space


COSMIC RAY Defined for Kids

cosmic ray

noun

Definition of cosmic ray for Students

  1. :  a stream of very penetrating particles that enter the earth's atmosphere from outer space at high speed


Learn More about cosmic ray


Seen and Heard

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

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

WORD OF THE DAY

cleverly stylish

Get Word of the Day daily email!

Test Your Vocabulary

Time Traveler Quiz: Which Word Came First?

  • time-traveler-quiz-which-word-came-first
  • Which came first?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!

TAKE THE QUIZ
Word Winder's CrossWinder

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

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!