A computer system that is capable of providing either full functionality (fail-safe) or reduced functionality (fail-soft) after a failure has occurred. Fault tolerance is usually provided through a combination of redundant system elements and error detection and correction procedures.
Internet
A system where a fault, be it a hardware or software fault, does not immediately lead to total failure. For example, such a system degrades gracefully when some fault occurs.
Electronics and Electrical Engineering
A system, often an electronic system, that by redundancy provides a service complying with the specification in spite of faults.