The Collaborative International Dictionary
Philippium \Phi*lip"pi*um\, n. [NL. So named from Philippe Plantamour, of Geneva, Switzerland.] (Chem.) A rare and doubtful metallic element said to have been discovered in the mineral samarskite.
n. (context chemistry obsolete English) A supposed metallic element obtainable from samarskite, later discovered to be a mixture of yttrium and terbium.