'group-stored' originates from the combination of 'group' and 'store', where 'group' meant 'a number of people or things that are located, gathered, or classed together' and 'store' meant 'to keep or accumulate something for future use'.

'group' and 'store' were combined in modern English to form the adjective 'group-stored'.

Initially, 'store' meant 'to keep or accumulate something', and 'group' referred to a collection. Together, they evolved to describe items stored collectively.