'fallback' originates from the combination of 'fall' and 'back', where 'fall' meant 'to descend' and 'back' referred to 'a return to a previous state'.

'fallback' evolved from the literal sense of 'falling back' in military terms to a more general use in planning and strategy.

Initially, it meant 'to retreat or withdraw', but over time it evolved into its current meaning of 'an alternative plan or strategy'.