early 15c., from Old French combustion (13c.), from Latin combustionem (nominative combustio) "a burning," noun of action from past participle stem of Latin comburere "to burn up, consume," from com-, intensive prefix (see com-), + *burere, faulty separation of amburere "to burn around," actually ambi-urere, from urere "to burn, singe," from PIE root *eus- "to burn" (see ember).
combustion com·bus·tion (kəm-bŭs'chən)
The process of burning.
A chemical change, especially oxidation, accompanied by the production of heat and light.