'dynast' originates from New Latin, specifically the word 'dynastes', where the Greek root 'dunast-' (from 'dunastēs') meant 'ruler' (ultimately from 'dunamai', 'to be able').

'dynast' changed from the Greek word 'dunastēs' to New Latin 'dynastes', and eventually was borrowed into modern English as 'dynast'.

Initially, it meant 'ruler' or 'one who has power'; over time it has retained that sense but is often used specifically for a member of a ruling family or dynasty.