oil 
(oil)
(oil)n.
1. Any of numerous mineral, vegetable, or synthetic substances or animal or vegetable fats that are generally slippery, combustible, viscous, liquid or liquefiable at room temperatures, soluble in various organic solvents such as ether but not in water, and used in a great variety of products, especially lubricants and fuels.
2.
a. Petroleum.
b. A petroleum derivative, such as a machine oil or lubricant.
3. A protective or cosmetic liquid applied to the skin or hair.
4. Oil paint.
5. A painting done in oil paint.
tr.v. oiled, oil·ing, oils
Idiom: To lubricate, supply, cover, or polish with oil.
oil (someone's) hand/palm Informal
1. To bribe: an attorney who tried to oil the judge's hand to obtain a favorable verdict.
2. To give a tip to: oiled the porter's palm.
[Middle English, from Old French oile, from Latin oleum, olive oil, from Greek *elaiwon, elaion, from *elaiwā, elaiā, olive.]