Source : Webster's Revised Unabridged Dictionary (1913)

Praseodymium \Pra`se*o*dym"i*um\, n. [Praseo- + didymium.]
   (Chem.)
   An elementary substance, one of the constituents of didymium;
   -- so called from the green color of its salts. Symbol Ps.
   Atomic weight 143.6.

Source : WordNet®

praseodymium
     n : a soft yellowish-white trivalent metallic element of the
         rare earth group; can be recovered from bastnasite or
         monazite by an ion-exchange process [syn: {Pr}, {atomic
         number 59}]