Dictionary entry

Terbium

Webster's Dictionary 1913

Ter″bi‐um (?), n. [NL., fr. Ytterby, in Sweden. See Erbium.] (Chem.) 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.