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.
Interestingly, the lifetimes achieved now surpass typical timescales for cosmic ray impacts, suggesting some level of insensitivity by cat qubits to such events. Neetika Walter, Interesting Engineering, 25 Sep. 2025 Mapping the heliosphere The heliosphere was first theorized by multiple scientists investigating the concept of cosmic rays and the solar wind in the late 1950s, according to NASA. Ashley Strickland, CNN Money, 24 Sep. 2025 Its few dozen inhabitants study climate, sea ice, cosmic rays, meteorology, glaciology and biodiversity. Jamie Carter, Space.com, 23 Sep. 2025 These particles, known as cosmic rays, are mostly composed of single protons, although heavier atomic nuclei, electrons, positrons (the antimatter counterpart of electrons), and neutrinos are all present as well. Ethan Siegel, Big Think, 4 Sep. 2025 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

Cite this Entry

“Cosmic ray.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/cosmic%20ray. Accessed 6 Oct. 2025.

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

Last Updated: - Updated example sentences
Love words? Need even more definitions?

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