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

See Examples For:

magic number

Europe were guaranteed to reach the magic number of 14½ points and there was nothing America could do about it.

From BBC ● Sep. 14, 2026

The Dodgers entered Wednesday’s game with the Cincinnati Reds with a magic number of seven to clinch their 13th National League West title in 14 seasons.

From Los Angeles Times ● Sep. 10, 2026

Still, there’s no magic number for the core CPI that guarantees the Fed’s next move — and there’s lots of moving parts.

From MarketWatch ● Sep. 9, 2026

Here the magic number is all-electric range: an EPA-estimated 52 miles.

From The Wall Street Journal ● Aug. 1, 2026

To conquer Spassky and become World Champion, he’d always needed to collect 12½ points, and a win would get him to that magic number.

From "Endgame" by Frank Brady

Related Words

• code
• confidential information
• key
• mystery