• synonyms


  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.
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Origin of porphyroid

First recorded in 1790–1800; porphyr(y) + -oid
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for porphyroid

Historical Examples

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

    The Andes and the Amazon

    James Orton

British Dictionary definitions for porphyroid


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