How to sign: belonging to an early stage of technical development; characterized by simplicity and (often) crudeness
"the crude weapons and rude agricultural implements of early man"; "primitive movies of the 1890s"; "primitive living conditions in the Appalachian mo;
Similiar / Same: primitive, rude
How to sign: a dark oil consisting mainly of hydrocarbons
Similiar / Same: petroleum, crude oil, rock oil, fossil oil
Categories: fossil fuel, oil
Within this category: residual oil