'insurmountable' originates from the prefix 'in-' meaning 'not' and the word 'surmount,' which comes from Old French 'surmonter,' meaning 'to rise above.'

'surmonter' transformed into the English word 'surmount,' and eventually became 'insurmountable' by adding the prefix 'in-' to indicate negation.

Initially, it meant 'not able to rise above,' and this meaning has largely remained the same in modern usage.