'fault-tolerant' originates from the combination of 'fault' and 'tolerant', where 'fault' refers to a defect or imperfection, and 'tolerant' means able to endure or withstand.

'fault-tolerant' was coined in the context of computer science to describe systems that can handle errors without failing.

Initially, it meant 'able to endure faults', and this meaning has largely remained the same in modern usage.