petrol

\ \ [16] Petrol originally meant ‘mineral oil, extracted from the ground’ (what we would now call petroleum or, more loosely, simply oil); not until the end of the 19th century was it applied to the ‘fuel refined from this’. The word was borrowed from French pétrole, which in turn came from Latin petroleum (itself taken over directly into English in the 16th century). This means etymologically ‘rock-oil’. It was formed from petra ‘rock’ and oleum ‘oil’. Other English words that go back to Latin petra or its Greek source pétrā include parsley, petrify [16], saltpetre [16] (so called because it forms a crust like salt on rocks), and the name Peter (a reference to Jesus calling the apostle Simon the ‘rock on which he would build his church’ – hence ‘Simon Peter’).

\ \ Cf.⇒ PARSLEY, PETRIFY, SALTPETRE