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petro- 1 WORD ORIGIN a combining form meaning “rock,” “stone,” used in the formation of compound words: petrology. Liberaldictionary.com
Also petri-; especially before a vowel, petr-. Origin of petro- 1Greek, combining form of pétra rock, pétros a stone petro- 2 a combining form meaning “petroleum,” “the extraction and export of petroleum,” used in the formation of compound words: petrochemistry; petropower. Origin of petro- 2extracted from petroleum Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019 British Dictionary definitions for petro- petro- before a vowel petr- combining form indicating stone or rockpetrology indicating petroleum, its products, etcpetrochemical of or relating to a petroleum-producing countrypetrostate Word Origin for petro- 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- 1
before vowels petr-, word-forming element used from 19c., from comb. form of Greek petros “stone,” petra “rock” (see petrous).
2
word-forming element used from mid-20c. to mean “of or having to do with petroleum products,” from petroleum.
Online Etymology Dictionary, © 2010 Douglas Harper petro- in Medicine petro- pref. Rock; stone; stone-like hardness:petrous. The American Heritage® Stedman’s Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.