noun-modifying (irregular)
internal combustion
Prenominal modifier used in technical terms such as 内燃機関 (internal combustion engine). Not used as a standalone noun.
Internal combustion engines use gasoline or diesel as fuel.
Hybrid vehicles that combine an internal combustion engine and an electric motor are increasing.
Compound of 内 (inside) and 燃 (burn), modeled after English 'internal combustion'.