D defs.my
Entry 1 sense Webster, 1913

hafnium

/(hăf"nē*ŭm or häf"nē*ŭm)/ · haf·ni·um · IPA /ˈhæfniəm/
01 n. 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,…
  1. 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. See: norium