unleaded
un-LED-id
/ˌʌnˈledɪd/
Petrol (gasoline) that has not been treated with toxic lead compounds.
Refers to standard modern automotive petrol; distinguished from leaded gas which was phased out due to environmental hazards.
The story behind the word. In the 1920s, tetraethyl lead was added to petrol to prevent engine knocking. When the toxic effects of lead emissions became widely recognized in the late 20th century, fuel without this additive was marketed as 'unleaded'.
Word relationships
- lead-free: Lead-free is a generic descriptive adjective, while unleaded is the standardized commercial term for fuel.
- leaded: Leaded fuel contains tetraethyl lead additive to increase octane rating.
Commonly confused with
- diesel: Unleaded is a classification of gasoline/petrol, whereas diesel is an entirely different hydrocarbon fuel formulation.
Collocations
- unleaded fuel
- unleaded petrol
- regular unleaded
- premium unleaded
Example sentences
- "Most modern passenger vehicles run on standard unleaded gasoline." Fuel selection
- "The worldwide mandate for unleaded fuel drastically reduced toxic heavy metal airborne pollution." Environmental history
Memory hook
UN-LEAD-ED = UN (without) toxic LEAD added. UNLEADED = Clean petrol free of toxic lead.
When not to use
Do not confuse with diesel; unleaded petrol is meant for spark-ignition engines, not compression diesel engines.
Fun facts
- Algeria became the last country in the world to end the sale of leaded gasoline for road vehicles in July 2021.
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