oil

Etymology 1

From Middle English oyle, oile (“olive oil”), borrowed from Anglo-Norman olie, from Latin oleum (“oil, olive oil”), from Ancient Greek ἔλαιον (élaion, “olive oil”), from ἐλαία (elaía, “olive”). Compare Proto-Slavic *lojь. More at olive. Supplanted Middle English ele (“oil”), from Old English ele (“oil”), also from Latin.

noun

1. Liquid fat.
2. petroleum-based liquid used as fuel or lubricant.
3. petroleum
   The dawn of the oil age was fairly recent. Although the stuff was used to waterproof boats in the Middle East 6,000 years ago, extracting it in earnest began only in 1859 after an oil strike in Pennsylvania. The first barrels of crude fetched $18 (around $450 at today’s prices). It was used to make kerosene, the main fuel for artificial lighting after overfishing led to a shortage of whale blubber. 2013-08-03, “Yesterday’s fuel”, in The Economist, volume 408, number 8847
4. (countable) An oil painting.
   Yet, in another way, I was unable to put Picasso's oils in the same class as Cezanne's, or even (which will no doubt shock many readers) as Renoir's. 1973, John Ulric Nef, Search for meaning: the autobiography of a nonconformist, page 89
5. (painting) Oil paint.
   I prefer to paint in oil
6. (attributive) Containing oil, conveying oil; intended for or capable of containing oil.
   oil barrel; oil pipe
   Such a vehicle is made by taking any old barrel (usually an oil barrel, but the one selected for our sketch was one that once contained Valentine’s varnish) and through each head of the barrel an inch hole is bored, and an iron bar is driven through, leaving the ends projecting about eight inches. 1884, Trade News, “A one-wheel Nantucket vehicle”, in The Automotive Manufacturer, page 372

Etymology 2

From Middle English oilen, oylen, from the noun (see above).

verb

1. (transitive) To lubricate with oil.
   The face which emerged was not reassuring. […]. He was not a mongol but there was a deficiency of a sort there, and it was not made more pretty by a latter-day hair cut which involved eccentrically long elf-locks and oiled black curls. 1963, Margery Allingham, chapter 17, in The China Governess
2. (transitive) To grease with oil for cooking.