combustion (n.)

"action or process of burning," early 15c., from Old French combustion (13c.) and directly from Latin combustionem (nominative combustio) "a burning," noun of action from past participle stem of Latin comburere "to burn up, consume," from com-, here probably an intensive prefix (see com-), + *burere, based on a faulty separation of amburere "to burn around," which is properly ambi-urere, from urere "to burn, singe," from PIE root *heus- "to burn" (see ember).