physicist who, with his aunt Lise Meitner (Meitner, Lise), described the division of neutron-bombarded uranium into lighter elements and named the process fission (1939). At the time, Meitner was working in Stockholm and Frisch at Copenhagen under Niels Bohr, who brought their observation to the attention of Albert Einstein and others in the United States.

After receiving his doctorate at Vienna (1926), Frisch, with Otto Stern and Immanuel Estermann, measured the magnetic moment of the proton (1933). During World War II he was engaged in atomic research at Los Alamos, N.M. From 1947 he taught at Cambridge and directed the nuclear physics department of the Cavendish Laboratory. His books include Atomic Physics Today (1961).