In the 1945 bombing of Hiroshima, what was the U.S. atomic bomb called?

In the 1945 bombing of Hiroshima, the U.S. atomic bomb was called Little Boy.

Little Boy was a uranium-235 gun-type nuclear weapon developed by the Manhattan Project. The U.S. Army Air Forces dropped it on Hiroshima on August 6, 1945, during the final weeks of World War II. The bomb exploded at approximately 8:15 a.m. local time.

The weapon was carried by the B-29 bomber Enola Gay, piloted by Colonel Paul Tibbets. Hiroshima was the first city to experience an atomic-bomb attack in wartime. The explosion and its effects killed tens of thousands of people immediately, with many more dying later from injuries and radiation exposure.

Little Boy is often confused with Fat Man, the different plutonium implosion weapon used against Nagasaki three days later. “Thin Man” was an earlier Manhattan Project design name, while “Pumpkin” referred to conventional practice bombs used in preparation for the atomic missions.