Senior managing editor and logophile Andy Hollandbeck reveals the sometimes surprising roots of common English words and phrases. Remember: Etymology tells us where a word comes from, but not what it means today.
Olive oil is a staple of the Mediterranean diet, and has been for centuries — in fact, in ancient Greece, the only true oil was olive oil, etymologically speaking.
The olive in Greek is called elaia, and the oil that came from those olives was called elaion. That elaion transformed into the Latin oleum, then the Old French oile, and finally the English oil. (The majority of European languages can trace their word for “oil” back to the same Greek root.)
For a long time, oil unadorned by some descriptor referred almost exclusively to olive oil. Around the beginning of the 12th century, the sense expanded somewhat to cover any greasy, insoluble liquid substance, and often one that would burn, but the sense even then was as a comparison to olive oil.
But in the early 15th century, people started to discover and experiment with a slick liquid substance that could be pulled from the earth. It was extracted from rock, so to name it, they stuck together the Latin oleum and the Latin word for “rock,” petrus (from the Greek petros). Thus we get petroleum, literally “rock oil.”
Today, (especially in cooking) a lot of oils are available — from avocado to walnut — but when the plain word oil is used, it most often means the caramel-colored stuff that lubricates a car engine. If you want to indicate what was once simply elaion, you have to be more specific. That makes olive oil, then, a good example of a centuries-old retronym — a newer term created from an existing word in order to differentiate it from a now more common meaning that has emerged through progress or development, such as cloth diaper, black-and-white TV, and manual transmission.
But olive oil is also practically a redundancy: The Greek elaia became the Latin oliva, which a few centuries later became the English olive. So both olive and oil find their etymological roots in the Greek name of a single type of tree that has long been an important part of Mediterranean life and cuisine.
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