petro-

1
Also petri-; especially before a vowel, petr-.

Origin of petro-

1
< Greek, combining form of pétra rock, pétros a stone

petro-

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

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-

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

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.
  1. 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.