'voluntarily' originates from Latin, specifically the word 'voluntarius,' where 'voluntas' meant 'will' or 'desire.' 'Assembled' comes from Old French 'assembler,' meaning 'to bring together.'

'voluntarius' transformed into the Old French 'voluntaire,' and eventually became the modern English word 'voluntary.' 'Assembler' evolved into the Middle English 'assemble,' leading to the modern English 'assemble.'

Initially, 'voluntarius' meant 'of one's free will,' and 'assembler' meant 'to gather.' These meanings have largely remained the same in modern usage.