'voluntarily-gathered' originates from the combination of 'voluntarily' and 'gathered', where 'voluntarily' comes from Latin 'voluntarius', meaning 'of one's free will', and 'gathered' from Old English 'gadrian', meaning 'to bring together'.

'voluntarily' changed from the Latin word 'voluntarius' and 'gathered' from the Old English word 'gadrian', eventually forming the modern English term 'voluntarily-gathered'.

Initially, 'voluntarily' meant 'of one's free will' and 'gathered' meant 'to bring together', and these meanings have largely remained the same in modern usage.