GRE TOEFL combustion Definition The process of burning something, typically with flame and heat. Example "The engine runs on internal combustion." Sign in to save GRE Quiz → TOEFL Quiz → ← combustible comedy → Study tips featuring "combustion" Write GRE Words Into Your Own Sentences TOEFL Academic Vocabulary: Study by Topic Related words GRE swill GRE taper GRE testy GRE abacus SAT abase GRE abash GRE abate GRE abbreviate GRE abbreviation SAT abdicate SAT abdomen GRE abduct