a radioactive, metallic chemical element, one of the actinides, produced by intense neutron bombardment of plutonium, as in a cyclotron: symbol, Fm; at. no., 100
See fermium in American Heritage Dictionary 4
(fûrˈmē-əm, fĕrˈ-)
noun Symbol Fm
A synthetic transuranic metallic element (atomic number 100) having 10 isotopes with mass numbers ranging from 248 to 257 and corresponding half-lives ranging from 0.6 minutes to approximately 100 days. See Table at element.