'collectively-decided' originates from the combination of 'collectively' and 'decided', where 'collectively' is derived from 'collective', meaning 'done by people acting as a group', and 'decided' is the past participle of 'decide', meaning 'to make a choice or come to a conclusion'.

'collectively' changed from the Latin word 'collectivus', and 'decided' from the Latin word 'decidere', eventually forming the modern English term 'collectively-decided'.

Initially, 'collectively' meant 'gathered together', and 'decided' meant 'to cut off', but over time, they evolved into their current meanings of 'done by a group' and 'to make a choice', respectively.