'Plagioclase' definitions:

Definition of 'plagioclase'

From: WordNet
noun
Any of a series of triclinic feldspars that form rocks [syn: plagioclase, oligoclase]

Definition of 'Plagioclase'

From: GCIDE
  • Plagioclase \Pla"gi*o*clase\, n. [Gr. pla`gios oblique + kla^n to break.] (Min.) A general term used of any triclinic feldspar. See the Note under Feldspar. [1913 Webster]