magic number

noun

, Physics.

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

magic number

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

magic number

/ 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.

Word History and Origins

Origin of magic number¹

First recorded in 1945–50

Example Sentences

Environmental engineers say a battery that runs at $20 per kilowatt-hour is the magic number for utilities to say goodbye to coal and natural gas—which is where Form Energy hopes to price Big Jim’s final product.

From Popular-Science

Anyone claiming their program can “balance” your hormones is misleading you, because there’s no magic number that everyone should strive for, and levels vary greatly between individuals and over time.

From Outside Online

This magic number was arrived at after one candidate was interviewed separately by 18 different people—and then rejected.

From The Daily Beast

The result was “Three is a Magic Number,” still my favorite Schoolhouse song.

From The Daily Beast

“Three is a Magic Number” becomes stunningly poignant to any couple that welcomes its first child.

From The Daily Beast

“We dickered back and forth and settled on .86 percent, not because it was a magic number,” said Hastert.

From The Daily Beast

The challenger needs 64 or more, and the incumbent, 69 or more, to get to the magic number of 270.

From The Daily Beast

Turning away from the curious throng, Mark cupped his hand, then together they all three peered at that magic number.

From Project Gutenberg

The ring becoming seven mountains suggests with its magic number an Oriental origin.

From Project Gutenberg

Its letters make up the magic number 365, supposed to represent the number of spirits subject to the supreme being.

From Project Gutenberg

Some conjurers say that number three is the magic number, and some say number seven.

From Project Gutenberg

I speak of Thirteen lands; and thirteen is as it were a magic number in the history of federations.

From Project Gutenberg

Related Words

• code
• confidential information
• key
• mystery