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See more synonyms for petro- on Thesaurus.com
  1. a combining form meaning “rock,” “stone,” used in the formation of compound words: petrology.
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Also petri-; especially before a vowel, petr-.

Origin of petro-1

< Greek, combining form of pétra rock, pétros a stone


  1. a combining form meaning “petroleum,” “the extraction and export of petroleum,” used in the formation of compound words: petrochemistry; petropower.
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Origin of petro-2

extracted from petroleum
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for petro-


before a vowel petr-

combining form
  1. indicating stone or rockpetrology
  2. indicating petroleum, its products, etcpetrochemical
  3. of or relating to a petroleum-producing countrypetrostate
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Word Origin

from Greek petra rock or petros stone
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

Word Origin and History for petro-


before vowels petr-, word-forming element used from 19c., from comb. form of Greek petros "stone," petra "rock" (see petrous).

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word-forming element used from mid-20c. to mean "of or having to do with petroleum products," from petroleum.

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Online Etymology Dictionary, © 2010 Douglas Harper

petro- in Medicine


  1. Rock; stone; stone-like hardness:petrous.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.