Definition

1. Noun:
   • A type of internal combustion engine: An engine that operates by compressing air to a high temperature and then injecting fuel (diesel oil) which ignites spontaneously due to the heat of the compressed air.
   • The fuel used in such engines: A heavy, oily fuel derived from petroleum, used in diesel engines. Also called diesel oil or diesel fuel.
   • A vehicle powered by a diesel engine: Informally, a vehicle (e.g., a car or truck) that uses a diesel engine.

Usage Examples

• Noun (Engine):
  • The truck is equipped with a powerful diesel.
  • Modern diesels are much quieter and more efficient than older models.
• Noun (Fuel):
  • The price of diesel has increased this week.
  • Please fill the tank with diesel, not gasoline.
• Noun (Vehicle):
  • He prefers driving a diesel for long journeys because of its fuel economy.

Advanced Usage

• "Diesel-electric": A hybrid drive system, typically used in locomotives and some large vehicles, where a diesel engine powers an electric generator which in turn drives electric motors.
  • The train was powered by a diesel-electric engine.
• "Diesel particulate filter (DPF)": An emissions control device that removes soot from the exhaust gas of a diesel engine.
  • The car's warning light indicated a problem with the diesel particulate filter.

Variants and Related Words

• Diesel engine (n): The full term for the engine type.
  • The invention of the diesel engine revolutionized heavy transport.
• Diesel fuel / Diesel oil (n): The specific fuel for diesel engines.
  • Diesel fuel is less volatile than gasoline.
• Diesel-powered (adj): Describing something that uses a diesel engine.
  • A diesel-powered generator.

Synonyms

• Compression-ignition engine: A more technical term for a diesel engine.
• Heavy oil: A general term for the type of fuel, though not exclusive to diesel.

Related Phrases

• To run on diesel: To use diesel fuel as an energy source.
  • Does this van run on diesel or petrol?
• Diesel exhaust: The gases emitted from a diesel engine.
  • Regulations aim to reduce harmful diesel exhaust.

Related Idioms

• "A diesel of a..." (informal, rare): Used to emphasize something as being very strong, powerful, or reliable, akin to the perceived qualities of a diesel engine.
  • That old tractor is a diesel of a machine; it never breaks down.

Noun

1. an internal-combustion engine that burns heavy oil
2. German engineer (born in France) who invented the diesel engine (1858-1913)