Manhattan Project

American  

noun

1. U.S. History. the unofficial designation for the U.S. War Department's secret program, organized in 1942, to explore the isolation of radioactive isotopes and the production of an atomic bomb: initial research was conducted at Columbia University in Manhattan.

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Manhattan Project British  

noun

1. (during World War II) the code name for the secret US project set up in 1942 to develop an atomic bomb

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Manhattan Project Cultural  

1. The code name for the effort to develop atomic bombs (see also atomic bomb) for the United States during World War II. The first controlled nuclear reaction took place in Chicago in 1942, and by 1945, bombs had been manufactured that used this chain reaction to produce great explosive force. The project was carried out in enormous secrecy. After a test explosion in July 1945, the United States dropped atomic bombs on the Japanese cities of Hiroshima (see also Hiroshima) and Nagasaki.

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Etymology

Origin of Manhattan Project

Extracted from U.S. Army Corps of Engineers Manhattan District and DSM (Development of Substitute Materials) Project

Example Sentences

See Examples For:

Manhattan Project

Under the veil of the Manhattan Project, this remote mesa became the site of a profound scientific pivot that ended a world war and ushered in the nuclear age.

From The Wall Street Journal ● Jul. 9, 2026

The atomic bomb remains a complicated topic, but the Manhattan Project revealed something extraordinary about America: Universities, government, soldiers, scientists and private companies came together under perilous circumstances to do what many had deemed impossible.

From The Wall Street Journal ● Jun. 26, 2026

We’ve had plagues and climate change before, to some degree, but until the Manhattan Project, humans weren’t really in control of that kind of existential, destructive power.

From Salon ● Jun. 15, 2026

Historically, Los Alamos served as the top-secret heart of the Manhattan Project, where the first atomic bombs were designed and built on an expedited timeline.

From Barron's ● Apr. 23, 2026

Leo Szilard and Eugene Wigner—the ones who’d triggered the Manhattan Project by convincing Albert Einstein to warn President Roosevelt of the danger of atomic bombs—came to watch.

From "Bomb" by Steve Sheinkin