origin: (1884) from Latin; ole(um) = Oleic (acid).
A British word for margarine; a product containing or associated with oil.
The French invented margarine in 1869, created from vegetable oil, unlike butter made from the butterfat in cow's milk. The advantage of oleo being its greatly increased shelf life. Oleo is also used in various pharmaceuticals, soaps, and aerosol products.
In recent years, the food products has become controversial as "transfats" (or partially hydrogenated oils) such as margarine have proven to have potentially cancerous side effects when ingested, thus resulting in its removal from many manufactured goods. Although, according to this article by Mother Jones, these products still commonly contain large quantities of oleo: canned frosting, crackers and microwave popcorn, pre-packaged pie, frozen pizza, margarine, coffee creamer. Oleic acid, from which oleo/margarine is concocted, is naturally odorless and colorless. In fact, if you go back toward WWII, you'd find a small food coloring packet that one was expected to mix in oneself! *For that appetizing yellow-orange color!
Lastly, a disgusting fact to share at parties (or with your little brother as he chows into breakfast), insects actually emit oleic acid when dead in order to signal the others to come and remove the bodies.
Sentence: "Her hair and smile were as slick and greasy as a plate of melted oleo."
1954 Vintage OLEOMARGARINE Magazine Advertisement