| an oil used for fuel, esp. one used as a substitute for coal, as crude petroleum. |
| fuel oil n. A liquid or liquefiable petroleum product that is used to generate heat or power. |
fuel oil
fuel consisting mainly of residues from crude-oil distillation. It is used primarily for steam boilers in power plants, aboard ships, and in industrial plants. Commercial fuel oils usually are blended with other petroleum fractions to produce the desired viscosity and flash point. Flash point is usually higher than that of kerosene. The term fuel oil ordinarily does not include such fuels as kerosene.
Learn more about fuel oil with a free trial on Britannica.com.