petro

¹ American  

[pe-troh] / ˈpɛ troʊ /

adjective

1. of or relating to petroleum or the petroleum industry.

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noun

1. Canadian. the federally owned petroleum industry.

petro- ² American  

1. a combining form meaning “rock,” “stone,” used in the formation of compound words.

   petrology.

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petro- ³ American  

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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petro- British  

combining form

1. indicating stone or rock

   petrology

2. indicating petroleum, its products, etc

   petrochemical

3. of or relating to a petroleum-producing country

   petrostate

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Usage

What does petro- mean? Petro- is a combining form used like a prefix that has two distinct senses.The first of these senses is “rock” or "stone," and this form of petro- is occasionally used in a variety of scientific and technical terms. Petro- comes from Greek pétra, meaning “rock.” Two Latin translations of pétra are lapis and saxum, both meaning “stone,” which are the roots of terms such as lapis lazuli and saxifrage, respectively. To learn more, check out our entries for both words.The second of these senses is “petroleum,” and this form of petro- is occasionally used in a variety of technical terms. Petro- is an abbreviation of the word petroleum, from the Medieval Latin word for "rock oil; the -oleum element means "oil" in Latin. Find out more about the word petroleum at our entry for the word.What are variants of petro- with the sense “rock”?Petri- is a variant of petro-, which exchanges its -o- for an -i- when combined with words or word elements beginning with certain consonants. Another variant for petro- in this sense is petr-, which loses its -o- combined with words or word elements beginning with vowels. Want to know more? Read our Words That Use articles for petri- and petr-.Not every word that begins with the exact letters petro- or petr-, such as petronel or petrel, is necessarily using the combining form petro- to denote “rock” or "petroleum.” Learn why petrel is the name of a seabird at our entry for the word.

Etymology

Origin of petro¹

First recorded in 1970–75; independent use of petro- ²

Origin of petro-²

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

Origin of petro-³

Extracted from petroleum

Example Sentences

Any real plan for reviving Venezuela’s oil industry has to reckon with the political legacy of the country’s long, turbulent history with its petro riches.

From The Wall Street Journal • Jan. 10, 2026

"Higher oil prices do allow low cost petro states to continue making investments in some of these decarbonized solutions, but only among this small group," said Mahdavi.

From Reuters • Mar. 3, 2022

The move has had no impact, in part because the petro isn’t traded.

From New York Times • Nov. 1, 2018

“Since mid-2015, we haven’t received any money from our petro dollars. The government refuses to pay, telling us it has no money to give.”

From Los Angeles Times • Jun. 17, 2018

Ships’ guns in those days were known as cannon, cannon royal, cannon serpentine, bastard cannon, demi-cannon, and cannon petro.

From How Britannia Came to Rule the Waves Updated to 1900 by Kingston, William Henry Giles