cosmic ray

noun

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

Examples of cosmic ray in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Not all involve capes or cosmic rays. — Gabrielle Principe, The Conversation, 5 May 2026 The phenomenon was discussed in the debrief as possibly tied to cosmic rays or heavy particles passing through the eye. — Sarah Rumpf-Whitten, FOXNews.com, 22 May 2026 Galactic cosmic ray exposure is the binding constraint on Mars crew transit. — Fred Kennedy, Forbes.com, 17 Apr. 2026 The galaxies also formed cosmic rays, the most highly energetic particles in the universe, which can create neutrinos. — Ashley Strickland, CNN Money, 26 June 2026 See All Example Sentences for cosmic ray

Word History

First Known Use

1925, in the meaning defined above

Time Traveler
The first known use of cosmic ray was in 1925

Rhymes for cosmic ray

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Browse Nearby Words

cosmic radiation
cosmic ray
cosmic-ray shower
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Cite this Entry

“Cosmic ray.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/cosmic%20ray. Accessed 7 Jul. 2026.

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Kids Definition

cosmic ray

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

More from Merriam-Webster on cosmic ray

Britannica.com: Encyclopedia article about cosmic ray

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