diesel

diesel — noun

1. A heavy oil that is burned inside engines to produce power. It is used mainly in

1.nounB1
Definition

A heavy oil that is burned inside engines to produce power. It is used mainly in cars, trucks, trains, and generators, and is thicker and less flammable than petrol.

Example

Camila filled her car with diesel at the petrol station near the highway.

Diesel costs less than petrol in many parts of Europe.

comparison: diesel vs petrol

Common collocations
  • diesel fuel
  • diesel oil
  • diesel tank
  • diesel pump
  • diesel prices
  • diesel fumes
  • diesel costs
Synonyms
  • fuel

    general term; diesel is one type of fuel, but 'fuel' can also refer to petrol, gas, coal, etc.

  • petrodiesel

    technical term for diesel derived from crude oil, distinguishing it from biodiesel

Antonyms
  • petrol

    also called gasoline; the lighter fuel used in spark-ignition engines

Usage Note

In this sense, diesel is uncountable — you cannot say 'a diesel' to mean the fuel. In British English, the fuel is sold at 'diesel pumps'; in American English, it is found at 'gas stations' alongside petrol.

Common Mistakes

I need to buy some diesel oil for my car.
I need to buy some diesel for my car.
'Diesel oil' is redundant; diesel is already understood as a type of fuel oil.
The petrol engine runs on diesel.
The diesel engine runs on diesel.
Petrol engines and diesel engines use different fuel types and are not interchangeable.

2. A truck, bus, train, or other powered transport that uses a diesel engine for po

2.nounB2
Definition

A truck, bus, train, or other powered transport that uses a diesel engine for power instead of a petrol engine.

Example

The new diesel trains are quieter and use less fuel than the old electric ones.

collocation: diesel train

Nikhil drives a diesel truck for a delivery company across the state.

Common collocations
  • diesel train
  • diesel truck
  • diesel car
  • diesel van
  • diesel locomotive
  • modern diesel
  • old diesel
Synonyms
Antonyms

Usage Note

In this countable sense, 'a diesel' or 'diesels' always refers to a vehicle — not the fuel or the engine alone. Context makes the meaning clear: 'We took a diesel' implies a diesel-powered train, bus, or truck depending on the situation.

Common Mistakes

I bought a diesel for my car.
I bought a diesel car.' or 'I filled my car with diesel.
Without context, 'a diesel' means a vehicle, not fuel. For the fuel, use the uncountable form 'diesel' without an article.
Diesels are more expensive than petrol.
Diesel cars are more expensive than petrol cars.
The comparison is clearer when you specify the type of vehicle.

3. An engine that burns diesel fuel instead of petrol. It uses high pressure to hea

3.nounB2
Definition

An engine that burns diesel fuel instead of petrol. It uses high pressure to heat the air inside the cylinders so the fuel catches fire on its own, without needing a spark plug.

Example

The diesel in this tractor is much more powerful than the old petrol engine.

Élise learned how a diesel ignites fuel by compression in her engineering class.

technical: compression ignition

Common collocations
  • diesel engine
  • diesel motor
  • diesel-powered
  • diesel generator
  • diesel pump
  • diesel injector
Synonyms
Antonyms
  • petrol engine

    also called a spark-ignition engine; uses spark plugs to ignite the fuel

Usage Note

In technical contexts, 'a diesel' (countable) means a diesel engine. The possessive form — 'the diesel's oil filter' — is common in automotive writing. Do not confuse with 'diesel' as fuel (uncountable, Sense 1).

Common Mistakes

My car has a diesel motor.
My car has a diesel engine.
'Diesel motor' is non-standard; 'diesel engine' is the conventional term.
The diesel runs on petrol.
The diesel runs on diesel fuel.
A diesel engine can only burn diesel, not petrol.

Word family

  • diesel-powered
    adjectiveB2
  • dieselisation
    nounC1
  • biodiesel
    nounC1

Synonym discussion

Sense: noun/1

These four words all relate to energy sources but differ in type and use. 'Diesel' is a specific heavy oil used in compression-ignition engines — common in trucks, trains, and generators. 'Petrol' (also called gasoline in American English) is a lighter fuel for spark-ignition engines in most cars. 'Fuel' is the broadest term: it covers diesel, petrol, coal, wood, gas, and any other substance burned to produce energy. 'Kerosene' (or paraffin) is a thin oil used in heaters, lamps, and some aircraft engines; it is lighter than diesel but heavier than petrol. A learner might say 'I filled up with fuel' (correct but vague), whereas specifying 'diesel' or 'petrol' gives precise information. For example: 'The truck needs diesel, not petrol' makes a critical distinction, while 'The generator runs on fuel' leaves the type unclear.

diesel ↗petrol ↗fuel ↗kerosene

Common collocations

Nouns

  • diesel engine
  • diesel fuel
  • diesel car
  • diesel train
  • diesel truck
  • diesel generator
  • diesel locomotive

Adverbs

  • diesel-powered
  • diesel-electric

Phrases

  • diesel exhaust fluid
  • diesel particulate filter
  • diesel engine oil

Prepositions

  • run on diesel
  • convert to diesel
  • switch to diesel

Etymology

GermanEnglish

The word 'diesel' comes from the name of Rudolf Diesel (1858–1913), a German mechanical engineer who invented the diesel engine in the 1890s. He designed an engine that used the heat from compressed air to ignite fuel, rather than a spark plug. The engine was first demonstrated at the 1900 World's Fair in Paris. Over time, the fuel itself came to be called 'diesel' as well, and later any vehicle using such an engine.