terbium > define
noun
- A metallic element of the rare earth group; used in lasers; occurs in apatite and monazite and xenotime and ytterbite.
- synonyms: Tb, atomic number 65
by WordNet 3.0 © 2006 by Princeton University
(n.) A rare metallic element, of uncertain identification, supposed to exist in certain minerals, as gadolinite and samarskite, with other rare ytterbium earth. Symbol Tr or Tb. Atomic weight 150.
by Webster's Revised Unabridged Dictionary