'astound' originates from Middle English, specifically the word 'astounen', from Old French 'estoner', ultimately from Latin 'extonare', where 'ex-' meant 'out' and 'tonare' meant 'to thunder'.

'astound' changed from Latin 'extonare' to Old French 'estoner', then to Middle English 'astounen', and eventually became the modern English word 'astound'.

Initially it meant 'to strike or deafen (as with thunder)', but over time it evolved into its current meaning of 'to astonish greatly'.