cosmic ray

noun

Definition of cosmic ray

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

Recent Examples of cosmic ray from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'cosmic ray.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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

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

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