Why did they name the atomic bombs?

Answer 1

The names Little Boy & Fat Man were military codenames, picked originally so that if they leaked to the enemy might sound like they were designing a custom airplane to carry FDR (Little Boy) & Churchill (Fat Man).

The general codename for Fat Man practice bombs carrying no plutonium was Pumpkin bombs. Several of these were dropped on Japanese cities in late july and early august to keep the crews in practice before the live bombs arrived.

Answer 2

It was a way to communicate in code without directly mentioning the bombs.

Little Boy (dropped on Hiroshima August 6, 1945) was a longer, thinner design that used uranium, which was exploded by firing one section of the material into another section.

Fat Man (dropped on Nagasaki August 9, 1945) was the same plutonium-based design as the first A-bomb, nicknamed The Gadget, that had been tested at Alamagordo in the Trinity test. It had a much larger circumference because sections of plutonium were blasted together into a sphere to form a critical mass.

Answer 3

The name atomic bomb originated in 1914 in H. G. Wells novel The World Set Free.

The atomic bomb obtains the energy for its explosion from the atomic nucleus.