Thulium

3 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Thulium \Thu"li*um\, n. [NL. See {Thule}.] (Chem.)
     A rare metallic element of the lanthanide group having atomic
     number 69, and atomic weight 168.93. It is found in the
     mineral gadolinite and other minerals, together with other
     rare earths. For more information see the data from
     ChemGlobe.


     [1913 Webster + PJC]

From WordNet (r) 2.0 [wn]:

  thulium
       n : a soft silvery metallic element of the rare earth group;
           isotope 170 emits X-rays and is used in small portable
           X-ray machines; it occurs in monazite and apatite and
           xenotime [syn: {Tm}, {atomic number 69}]

From Elements database 20001107 [elements]:

  thulium
  Symbol: Tm
  Atomic number: 69
  Atomic weight: 168.934
  Soft grey metallic element that belongs to the lanthanoids. One natural
  isotope exists, Tm-169, and seventeen artificial isotopes have been
  produced. No known uses for the element. Discovered in 1879 by Per Theodor
  Cleve.