'Petroleum' is a Greek-Latin hybrid meaning 'rock-oil' — from 'petra' (rock) + 'oleum' (oil).
A naturally occurring liquid mixture of hydrocarbons found beneath the earth's surface, refined to produce fuels, lubricants, and petrochemical feedstocks; crude oil.
From Medieval Latin 'petroleum,' literally 'rock-oil,' compounding Greek 'pétra' (πέτρα, rock, stone) and Latin 'oleum' (oil). The term was coined to describe the oily substance that seeped from rocks and the ground in certain regions. Greek 'pétra' derives from Proto-Indo-European *per- (to strike, cut through rock), and Latin 'oleum' from Greek 'élaion' (olive oil), from 'elaía' (olive tree
The name 'Peter' and the word 'petroleum' share the same Greek root: 'pétra' (rock). When Jesus said to Simon 'You are Peter, and on this rock I will build my church,' he was making a pun on the Greek word that, centuries later, would also name the substance that built the modern industrial economy.