referendum (n.)youdaoicibaDictYouDict[referendum 词源字典]
1847, "a submitting of a question to the voters as a whole" (originally chiefly in reference to Switzerland), from French or German, from Latin referendum "that which must be referred," literally "thing brought back," neuter gerundive of referre "to bring or take back" (see refer). As a gerundive, it has no plural in Latin; referendums is preferred in English.[referendum etymology, referendum origin, 英语词源]