WordReference Random House Unabridged Dictionary of American English © 2025
por•phy•roid
(pôr′fə roid′),USA pronunciation n.
- Rocksa rock resembling porphyry.
- Rocksa sedimentary rock that has been metamorphosed so as to leave some original crystals in a fine-textured, layered matrix.
- porphyr(y) + -oid 1790–1800