Etymology
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spearmint (n.)
1530s, from spear (n.2) + mint (n.1). "Said to be a corruption of spire-mint, with reference to the pyramidal inflorescence" [Century Dictionary].
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oil (n.)

late 12c., "olive oil," from Anglo-French and Old North French olie, from Old French oile, uile "oil" (12c., Modern French huile), from Latin oleum "oil, olive oil" (source of Spanish, Italian olio), from Greek elaion "olive tree," from elaia (see olive).

Nearly all the European languages' words for "oil" (Croatian ulje, Polish olej, Hungarian olaj, Albanian uli, Lithuanian alejus, etc.) are from the Greek word; the Germanic (except Gothic) and Celtic one coming from Greek via Latin: Old English æle, Dutch olie, German Öl, Welsh olew, Gaelic uill, etc. 

In English it meant "olive oil" exclusively till c. 1300, when the word began to be extended to any fatty, greasy liquid substance (usually flammable and insoluble in water). Often especially "oil as burned in a lamp to afford light" (as in midnight oil, symbolizing late work). Use for "petroleum" is recorded from 1520s but not common until 19c.

The artist's oils (1660s), short for oil-color (1530s), are paints made by grinding pigment in oil. Oil-painting is attested from 1782.  The ocean-going oil-tanker is from 1900; oil-spill is from 1970. As a condiment, oil and vinegar is attested from 1620s. The figurative expression pour oil upon the waters "appease strife or disturbance" is by 1840, from an ancient trick of sailors.

Another historical illustration which involves monolayers, was when sailors poured oil on the sea in order to calm 'troubled waters' and so protect their ship. This worked by wave damping or, more precisely, by preventing small ripples from forming in the first place so that the wind could have no effect on them. [J. Lyklema, "Fundamentals of Interface and Colloid Science," Academic Press, 2000]

The phenomenon depends on what are called Marangoni effects; Benjamin Franklin experimented with it in 1765.

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oil (v.)

"to smear or rub with oil or ointment," mid-15c., oilen, from oil (n.). Later especially "to lubricate (machinery)." Related: Oiled; oiling. An Old English verb in this sense was besmyrian.

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oil-skin (n.)

also oilskin, "cloth of cotton, linen, etc., prepared with oil to make it water-proof," 1816, from oil (n.) + skin (n.).

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oil-cloth (n.)

also oilcloth, 1690s, "cotton or a similar fabric waterproofed with oil," from oil (n.) + cloth. In reference to an oil-treated canvas used as a cheap floor covering, 1796.

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oil-well (n.)

"a boring in the earth made for petroleum," 1847, from oil (n.) + well (n.).

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oil-can (n.)

"can for holding oil," especially one with a long, narrow, tapering spout, used to oil machinery, 1839, from oil (n.) + can (n.).

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snake oil (n.)

1927 as "phony remedy," American English, from the use of oil derived from the fat of snakes (especially the rattlesnake) as a folk remedy in the rural regions of the U.S. Snake oil in this sense is attested by 1858. It was a folk remedy for rheumatism and gout in Georgia, but a cure for deafness in rural Pennsylvania. Professional pharmacy journals began to condemn it early 20c., not because it was quackery but because products sold under the name had no real snake oil in them.

What is known as snake oil is usually a combination which is handed out by the dealer to satisfy the demand of some credulous customer. A genuine oil of course is that which is obtained by "trying out" the fat of a snake, usually the rattlesnake, and to preserve their faces druggists sometimes employ a small proportion of such oil in preparing the weird mixtures dispensed by them. [The Practical Druggist, July 1912]
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oil-mill (n.)

"a crushing- or grinding-machine for expressing oil from seeds, fruits, nuts, etc.," early 15c., from oil (n.) + mill (n.1).

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oil-tank (n.)

"tank for holding oil," 1862, from oil (n.) + tank (n.).

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