Szilard, Leo Syllabification: (Szi·lard, Leo)Pronunciation: /ˈzilˌärd, ˈsil-, -ərd/Definition of Szilard, Leo (1898–1964), US physicist and molecular biologist, born in Hungary. He fled from Nazi Germany to the US, where he became a central figure in the Manhattan Project, which developed the atom bomb. Szilard, Leo in other Oxford dictionaries Definition of Szilard, Leo in the British & World English dictionary