'revengefully' originates from the English word 'revengeful', which is derived from the word 'revenge', itself coming from the Old French 'revenger', meaning 'to avenge'.

'revenge' changed from the Old French word 'revenger' and eventually became the modern English word 'revenge'.

Initially, it meant 'to avenge or retaliate', but over time it evolved into its current meaning of 'seeking revenge'.