Meaning of porphyroid

por•phy•roid

Pronunciation: (pôr'fu-roid"), [key]
— n.
  1. a rock resembling porphyry.
  2. a sedimentary rock that has been metamorphosed so as to leave some original crystals in a fine-textured, layered matrix.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.