petro-, petr-, petri-, peter-

(Greek > Latin: stone, rock)

petrography (s) (noun), petrographies (pl)
The scientific description of the composition and formation of rocks: Petrography is the systematic classification of igneous and metamorphic stones on the basis of their mineralogical and textural relationships; especially, by means of microscopic studies.
petrol (s) (noun), petrols (pl)
1. A British term for gasoline, or gas, for motor-driven vehicles: On their holiday in England Jerry and Janice stopped at a fuel station to fill their rented car with petrol.
2. Any of numerous organic compounds; such as, benzene and methane, that contain only carbon and hydrogen; including octane, heptane, hexane, etc., which are extracted from petroleum; primarily used as a fuel in internal-combustion engines: Petrol is known to contain such ingredients as corrosion inhibitors and antiknock compounds and lighter hydrocarbons from gasoline that can be used in dirigible balloons.
3. Etymology: "gasoline" from French pétrol (1892); earlier used (1585) in reference to the unrefined substance, from Middle French petrole, "petroleum"; from Old French; from Modern Latin petroleum.
petrolatum (s) (noun), petrolatums (pl)
A translucent, oily, semisolid, amorphous, yellowish or whitish mass obtained from petroleum: Petrolatum is used as a lubricant, as a rust preventive, and in cosmetics and medicine as a protective dressing, emollient, or an ointment.
petroleous (adjective), more petroleous, most petroleous
Relating to something that is abounding in or containing a slippery or viscous liquid or liquefiable substance that cannot be mixed with water: Sam was astounded when he found out that he actually had petroleous resources on his property and so it was possible to obtain a lot of oil and that is why he contacted the local refinery to see when it could start the process of collecting it.
petroleum (s) (noun), petroleums (pl)
A naturally occurring liquid mixture of complex hydrocarbon compounds that yields combustible fuels, petrochemicals, and lubricants upon distillation; usually found in deposits beneath the earth's surface and thought to have originated from plant and animal remains of the geologic past: Petroleum is by far the most widely used fuel source in the industrialized world and it is also used in many industrial products; such as, plastics, synthetic fibers, and drugs.
petrolic (adjective), more petrolic, most petrolic
Pertaining to something that is produced from oil: When Tom went to the gas station to get some gas for his car, little Susi, who sat in the back seat, was fascinated by the petrolic odor which came in through her open window.
petroliferous (adjective), more petroliferous, most petroliferous
Descriptive of geological formations that contains or consists of a thick, dark, and smooth liquid from under the ground which is used for making gas and other fuels: There are petroliferous sandstones and petroliferous shale oils located in various parts of the world.
petrologic (adjective), more petrologic, most petrologic
Relating to the devision of science concerned with the study of various geological formations: Jack’s petrologic research included research in the origin, history, structure, and the categorizing of inorganic materials; such as, gravel, cliffs, mountains, etc.
petrological (adjective), more petrological, most petrological
Descriptive of the field of knowledge dealing with inorganic matter: Troy's petrological studies have revealed the microscopic details of the compositions of gemstones and minerals.
petrologically (adverb), more petrologically, most petrologically
Pertaining to how rocks originate, are composed, are structured and are systemized: Jane worked quite petrologically while identifying the gems and precious stones she had to analyze for her geology class at school.
petrologist (s) (noun), petrologists (pl)
A person who is a specialist in the field of large and small boulders: A famous petrologist was invited to be a guest speaker at Calvin's university and to give a talk about the composition and texture of igneous matter; such as, slate, marble, granite, and schist or fine-grained sandstone, etc.
petrology (s) (noun), petrologies (pl)
The scientific study of stones: Petrology includes the academic research of the occurrence, the chemical composition and classification of quartz, geodes, chalk, obsidian, etc.
petrophile (s) (noun), petrophiles (pl)
Evergreen shrubs (of the family Proteaceae) found in Australia, New South Wales and Queensland: These bushes are usually known as conebushes that have prickly leafage and yellow or pink flowers which then produce gray, conical fruits.
petrophilous (adjective), more petrophilous, most petrophilous
In biology, descriptive of something that  thrives on rocks or in stony habitats: Most species of rattlesnakes found in the Mojave Desert live among the open, rocky areas, often hiding out of the sun in the cracks of boulders.
A wildcat and plants that exist on rocky areas.
—Source: Natur-Palette , Zurich Insurance Calendar, 1992.
petrophily (s) (noun), petrophilies (pl)
An organism which has its habitat in areas with stones or lapideous regions: Some petrophilies, like the chuckwalles,  are rock-dwelling creatures, vegetarians and feed on leaves, flowers and fruits of any desert plants.

Related "stone, rock" word families: lapid-; litho-; saxi-; stele-.