magic number

American  

noun

Physics.

1. the atomic number or neutron number of an exceptionally stable nuclide.

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magic number British  

noun

1. physics any of the numbers 2, 8, 20, 28, 50, 82, and 126. Nuclides with these numbers of nucleons appear to have greater stability than other nuclides

2. chem a number of atoms that is particularly stable in certain types of compound that have clusters of the same type of atom

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magic number Scientific  

/ măj′ĭk /

1. Any of the numbers, 2, 8, 20, 28, 50, 82, or 126, that represent the number of neutrons or protons in strongly bound and exceptionally stable atomic nuclei. The existence of such stable nuclei is explained by assuming a shell structure for nucleons, much like the shell structure of electron orbitals around the nucleus.

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Etymology

Origin of magic number

First recorded in 1945–50

Example Sentences

The “magic number” that Americans think they need to retire comfortably totaled $1.26 million, according to a study earlier this year from Northwestern Mutual.

From MarketWatch

After ending their embarrassing Test losing streak at 18 in Japan last summer, 12 is the magic number for Wales when they host the Brave Blossoms in Cardiff.

From BBC

Read: Amazon’s stock comeback hinges on AWS hitting this magic number.

From MarketWatch

There are the parents who want to know what the “magic number” is to donate to guarantee admission.

From The Wall Street Journal

In a 5-4 extra-innings win over the Arizona Diamondbacks that lowered their magic number to clinch the National League West to one, the Dodgers again squandered a late-game lead when their traditional relievers faltered.

From Los Angeles Times

Related Words

• code
• confidential information
• key
• mystery