an extremely radioactive, metallic chemical element, one of the actinides, generally produced by neutron bombardment of plutonium or americium: symbol, Cm; at. no., 96
See curium in American Heritage Dictionary 4
cu·ri·um
noun Symbol Cm
A silvery metallic synthetic radioactive transuranic element. Its longest lived isotope is Cm 247 with a half-life of 16.4 million years. Atomic number 96; melting point (estimated) 1,350°C; valence 3. See Table at element.