'astonishment' originates from Old French (via Middle English), specifically from the verb 'estoner' (Old French) derived from Vulgar Latin *'extonare', where the root 'tonare' meant 'to thunder' and the prefix 'ex-' meant 'out' or 'thoroughly'.

'astonish' changed from Old French 'estoner' (meaning 'to stun, amaze') into Middle English forms such as 'astonen' or 'astonish', and the noun 'astonishment' developed by adding the suffix '-ment' to form the modern English 'astonishment'.

Initially, it carried the sense of being 'stunned or struck (as by thunder)', but over time it evolved to the current general sense of 'great surprise or amazement'.