WordNet (r) 3.0 (2006):

technetium
    n 1: a crystalline metallic element not found in nature; occurs
         as one of the fission products of uranium [syn:
         technetium, Tc, atomic number 43]

The Elements (07Nov00):

technetium
Symbol: Tc
Atomic number: 43
Atomic weight: (98)
Radioactive metallic transition element. Can be detected in some stars
and
the fission products of uranium. First made by Perrier and Segre by
bombarding molybdenum with deutrons, giving them Tc-97. Tc-99 is the
most
stable isotope with a half-life of 2.6*10^6 years. Sixteen isotopes are
known. Organic technetium compounds are used in bone imaging. Chemical
properties are intermediate between rhenium and manganese.