'indefensible' originates from Latin, specifically the word 'indefensibilis,' where 'in-' meant 'not' and 'defensibilis' meant 'capable of being defended.'

'indefensibilis' transformed into the Old French word 'indefensible,' and eventually became the modern English word 'indefensible' through Middle English.

Initially, it meant 'not capable of being defended,' and this meaning has largely remained the same in modern usage.