Oppenheimer (??p?n?ha?m?) n (Biography) J(ulius) Robert. 1904?67, US nuclear physicist. He was director of the Los Alamos laboratory (1943?45), which produced the first atomic bomb. He opposed the development of the hydrogen bomb (1949) and in 1953 was alleged to be a security risk. He was later exoneratedCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014Op?pen?heim?er (??p ?n?ha? m?r) n. J(ulius) Robert, 1904?67, U.S. nuclear physicist. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.