WordNet (r) 3.0 (2006):

americium
    n 1: a radioactive transuranic metallic element; discovered by
         bombarding uranium with helium atoms [syn: americium,
         Am, atomic number 95]

The Elements (07Nov00):

americium
Symbol: Am
Atomic number: 95
Atomic weight: (243)
Radioactive metallic transuranic element, belongs to the actinoids. Ten
known isotopes. Am-243 is the most stable isotope, with a half-life of
7.95*10^3 years. Discovered by Glenn T. Seaborg and associates in 1945,
it
was obtained by bombarding uranium-238 with alpha particles.