'arsonate' originates from English, ultimately built on the noun 'arson' which comes from Old French 'arsion' (from Latin 'ardēre'), where the root meant 'to burn'.

'arsonate' was formed in modern English by attaching the verb-forming suffix '-ate' to the noun 'arson' (itself from Old French 'arsion' < Latin 'ardēre'), producing a verb meaning 'to cause or perform arson'.

Initially the related roots simply meant 'to burn'; over time the English formation 'arsonate' came to mean specifically 'to commit arson' (deliberately set fire).