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.
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.