[ pawr-fuh-roid ]
/ ˈpɔr fəˌrɔɪd /


a rock resembling porphyry.
a sedimentary rock that has been metamorphosed so as to leave some original crystals in a fine-textured, layered matrix.

Origin of porphyroid

First recorded in 1790–1800; porphyr(y) + -oid
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Examples from the Web for porphyroid

  • Pumice and trachyte are the most common rocks around this mountain, and these are augitic or porphyroid.

British Dictionary definitions for porphyroid

/ (ˈpɔːfɪˌrɔɪd) /


(of metamorphic rocks) having a texture characterized by large crystals set in a finer groundmass


a metamorphic rock having this texture
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012