The Collaborative International Dictionary of English v.0.48:

Samarium \Sa*ma"ri*um\, n. [NL., fr. E. samarskite.] (Chem.)
   A rare metallic element of doubtful identity.
   [1913 Webster]

   Note: Samarium was discovered, by means of spectrum analysis,
         in certain minerals (samarskite, cerite, etc.), in
         which it is associated with other elements of the
         earthy group. It has been confounded with the doubtful
         elements decipium, philippium, etc., and is possibly a
         complex mixture of elements not as yet clearly
         identified. Symbol Sm. Provisional atomic weight 150.2.
         [1913 Webster]

WordNet (r) 3.0 (2006):

samarium
    n 1: a grey lustrous metallic element of the rare earth group;
         is used in special alloys; occurs in monazite and
         bastnasite [syn: samarium, Sm, atomic number 62]