'unbearable' originates from Middle English, specifically the word 'unberable,' where 'un-' meant 'not' and 'beran' meant 'to bear.'

'unberable' transformed into the modern English word 'unbearable' through the addition of the suffix '-ness' to form 'unbearableness.'

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