n. a hydrocarbon oil found in the upper strata of the earth, refined for use as a fuel for heating and in internal-combustion engines, for lighting, dry-cleaning, etc.
Phrases and idioms:
petroleum ether a volatile liquid distilled from petroleum, consisting of a mixture of hydrocarbons. petroleum jelly a translucent solid mixture of hydrocarbons used as a lubricant, ointment, etc.
Etymology: med.L f. L petra rock f. Gk + L oleum oil