Definition of diesel noun from the Oxford Advanced Learner's Dictionary

diesel

noun
ˈdiːzl
 
; ˈdiːzl
 
 
1 (also diesel fuel, diesel oil) [uncountable] a type of heavy oil used as a fuel instead of petrol/gasa diesel engine(= one that burns diesel )diesel cars/locomotives/trains compare petrol2 [countable] a vehicle that uses diesel fuelOur new car is a diesel.