noun

1. the act or process of burning
2. rapid oxidation accompanied by heat and, usually, light, as with magnesium
3. slow oxidation accompanied by relatively little heat and no light, as with a carbohydrate
4. violent excitement or agitation; tumult

Etymology: ME < OFr < LL combustio < L combustus, pp. of comburere (for *com-urere), to burn < com-, intens. + *burere (by faulty separation of amburere, to burn around < ambi-, ambi- + urere, to burn, singe): see ember