'stably-fastened' originates from the combination of 'stable' and 'fasten', where 'stable' meant 'firmly fixed' and 'fasten' meant 'to attach or secure'.

'stable' and 'fasten' were combined in modern English to form the compound adjective 'stably-fastened'.

Initially, 'stable' meant 'firmly fixed' and 'fasten' meant 'to attach or secure', and this meaning has largely remained the same in modern usage.