'overgenerous' originates from the prefix 'over-' meaning 'excessive' and the word 'generous' from Latin 'generosus', meaning 'noble' or 'magnanimous'.

'generosus' transformed into the Old French word 'genereux', and eventually became the modern English word 'generous'. The prefix 'over-' was added to indicate excessiveness.

Initially, 'generous' meant 'noble' or 'of noble birth', but over time it evolved into its current meaning of 'liberal in giving'.