Have you ever read the ingredients of Dream Whip dessert topping and wonder what "edible oil" meant? When I was younger, my sister and I thought that meant petroleum-based oil products were being put in our food. I now know that edible oils are actually (most often) plant-based oils, similar, if not the same as those produced by the industrial biotech industry for use as biofuels such as biodiesel, for use in cosmetics, and in other everyday biotech products.
Edible oils are defined by the Government of Ontario, Canada as "a food substance, other than a dairy product, of whatever origin, source or composition that is manufactured for human consumption wholly or in part from a fat or oil other than that of milk". The US FDA seems to differentiate (based on literature on their website) between edible vegetable oils and animal fats but I couldn't find a definition for edible oils on their website.
Plant-derived edible oils consist of carboxylic acids with long hydrocarbon chains, in contrast to petroleum-based oils which lack the carboxyl group on the end. The carboxyl group is what makes the oils edible, providing a site for our enzymes to attack and break down the chain in a process called beta-oxidation. The lengths of the hydrocarbon chains and whether they are saturated or not, or unsaturated in a cis or trans conformation, determines how easily they are metabolized and how healthy or unhealthy they are as part of our diet.