A mineral oil is any of various colorless, odorless, light mixtures of alkanes in the C15 to C40 range from a non-vegetable (mineral) source, particularly a distillate of petroleum.

The name mineral oil by itself is imprecise, having been used to label many specific oils over the past few centuries. Other names, similarly imprecise, include white oil, liquid paraffin, and liquid petroleum.

Most often, mineral oil is a liquid by-product of the distillation of petroleum to produce gasoline and other petroleum-based products from crude oil. A mineral oil in this sense is a transparent, colorless oil composed mainly of alkanes and cyclic paraffins, related to petroleum jelly (also known as "white petrolatum"). It has a density of around 0.8 g/cm³. Mineral oil is a substance of relatively low value, and it is produced in very large quantities. Mineral oil is available in light and heavy grades, and can often be found in drug stores.

There are three basic classes of refined mineral oils:

Some of the imprecision in the definition of the names (e.g., "mineral oil", "white oil") reflects usage by buyers and sellers who did not know, and usually did not need to care about, the precise chemical makeup. Prior to the late 19th century, the chemical science to determine such makeup was unavailable in any case, so the fact that one name ended up applied to various oils is unsurprising. A similar lexical situation occurred with the term "white metal".