see the periodic table of elements in the Reference Supplement
a radioactive chemical element, one of the rare-earth elements, obtained from fission
of uranium or neutron
bombardment of neodymium
and used in phosphorescent paint
, as a power source, X-ray
source, etc.: symbol, Pm; at. no., 61
Webster’s New World College Dictionary, 4th Edition. Copyright © 2010 by
Houghton Mifflin Harcourt. All rights reserved.
Word origin of 'promethium'
ModL: so named (1949) for earlier prometheum
, name proposed by G. M. Coryell for element isolated (1948) by J. A. Marinsky & L.
E. Glendenin, U.S. physicists < Gr Promētheus
) in reference to production by nuclear fission + -ium