mass number


: an integer that approximates the mass of an isotope and designates the number of nucleons in the nucleus

Examples of mass number in a Sentence

Recent Examples on the Web Davis spent years programming bots to attack e-commerce sites to buy up mass numbers of limited-edition athletic shoes. Ash-Har Quraishi, CBS News, 8 Feb. 2024 The downturn couldn’t have come at a worse time, considering that moviegoers are showing signs of life in terms of returning to the cinema in mass numbers. Pamela McClintock, The Hollywood Reporter, 15 Dec. 2023 People lost jobs in mass numbers in early 2020, and the government tried to soften the blow with multiple relief packages. Ben Casselman, New York Times, 19 Oct. 2023 Tom Cruise Is Doing an 'Oppenheimer' and 'Barbie' Double Feature Too: 'Doesn't Get More Explosive' Murphy’s excitement over the two films has mirrored that of fans, as there has been a mass number of bookings to see Oppenheimer and Barbie as a double feature in theaters. Escher Walcott, Peoplemag, 12 July 2023 Mass customization is all about creating a mass number of products that are all different, tailored specifically for each individual customer. John Clemons, Forbes, 21 Apr. 2022 The Wisconsin Department of Agriculture, Trade and Consumer Protection is reminding consumers of their right to a refund given the mass number of cancellations because of COVID-19. Hope Karnopp, Milwaukee Journal Sentinel, 11 Aug. 2021 Somehow, the mass number of people upgrading to Big Sur on Thursday seems to have caused the servers at to become overloaded but not fall over completely. Dan Goodin, Ars Technica, 16 Nov. 2020 But the city's unrest continues to stem from the horrifying footage of Blake's shooting and the mass number of unarmed Black men who have been the target of police violence., 26 Aug. 2020

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'mass number.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1923, in the meaning defined above

Time Traveler
The first known use of mass number was in 1923

Dictionary Entries Near mass number

Cite this Entry

“Mass number.” Dictionary, Merriam-Webster, Accessed 20 May. 2024.

Kids Definition

mass number

: a whole number that expresses the approximate mass of an atom in terms of the number of protons and neutrons in the atom

Medical Definition

mass number

: an integer that approximates the mass of an isotope and that designates the number of nucleons in the nucleus
the symbol for carbon of mass number 14 is 14C or C14
compare atomic mass

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