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.
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, oilsIdiom:
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.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.