The oil expressed from the fruit of Olea europoea. Olive oil is composed of a fluid oil, olein; a solid oil, palmitin; with oleic and palmitic acids.

Used externally by inunction, it is absorbed by the lymphatics, and has some nutritive value.

As a mechanical application it is used both externally and internally in the treatment of burns and corrosive poisons. It acts as a laxative, and is used for this purpose in enemata, tending to soften the faecal mass and assist in its expulsion. Oils in general are changed into carbonic acid and water in the system, and so excreted, but an excess will appear unchanged in the urine.