'combust' originates from Latin, specifically the word 'combustus,' where 'com-' meant 'together' and 'bust' meant 'to burn.'

'combustus' transformed into the Old French word 'combust,' and eventually became the modern English word 'combust' through Middle English.

Initially, it meant 'to burn together,' but over time it evolved into its current meaning of 'to catch fire or cause to catch fire.'