hafnium /(hăf"nē*ŭm or häf"nē*ŭm)/

haf·ni·um

hafnium

n.
  1. A metallic element of atomic number 72 present together with zirconium to the extent of 1% to 5% in zirconium minerals. It is a poisonous, ductile metal with a brilliant silver luster, has an atomic weight of 178.49, and has a high melting point (2227° C). It is used in nuclear reactors, and incandescent lamps as a scavenger of oxygen and nitrogen. See also norium.